Principles of sleeping bag design   Determine the Purpose of the Sleeping Bag   Determine the Shape Rectangular Style Sleeping Bag   Mummy Style Sleeping Bag   Hybrid style sleeping bag    Determine the Size   Determine Temperature Rating   Determine Insulation   Determine the Lining   Pricing   CARE & STORAGE Terminology for all the different types of materials used

 
A well-chosen bag will fit the person using it, be easy to pack, store and care for, and suit the temperature it's being used for.

Sleeping bags are pretty much unnecessary for typical family summer camping.
One or two light wool or fluffy acrylic blankets,  will provide plenty of warmth in temperatures to 45 degrees.

 All you really need is a
basic rectangle Sleeping bag
 for cushion if anything else!

For a child, the light-weight cotton ones will be fine. 
They can be found in almost every department or discount store, frequently in popular cartoon character designs, for $10 on up.
If for any reason all you have for a child is an adult basic rectangle Sleeping bag, you can always custom fit it to fit your child in the diagram below . . .

For an outdoor experience, you may want to shop carefully for one in the right size, shape, warmth, fabric, weight, and price that's perfect for your camping needs.

Principles of sleeping bag design

1. The smaller the bag, the less area it will have to insulate. Translation: Confining mummy bags are much warmer for their weight than roomy rectangular ones.

2. Most heat loss from a sleeping bag occurs through the open head end.
 It's nearly impossible to seal the open end of a rectangular style sleeping bag so that warm air won't escape.
(One solution is to install a collar - see diagram above for details.) For this reason integral hoods are mandatory on sleeping bags that will be used for cold weather camping.

Tip: An effective makeshift collar can be made from a sweater or scarf. Drape the garment across your chest and bunch the fabric around your neck and shoulders, feathering it to the adjacent sleeping bag fabric. This will eliminate drafts and increase warmth.

3. A full length zipper which runs from foot to chin is a must.
 Bags with half-length zippers become impossibly hot in warm weather.

Bag Anatomy
By Nancy Prichard

When you buy a bag, any bag, there are several features you should check. Start at the top.

Hood. Most bags have a hood that can be drawn tight around your head in cold weather. Up to 50 percent of your body's heat can be lost through your head, so a good hood can greatly improve the efficiency of your bag. Get in the bag and pull the drawstring. Can you still breathe with the hood in place? Can you turn, or roll, without suffocating? A hood should have slightly more fill material than the rest of the bag, and when in place, still have room to accommodate a cap. Draft collar. Scrutinize the draft collar, which is at the base of the hood. This insulated tube is designed to prevent heat loss from around your neck and shoulders. Rectangular, summer bags may not have draft collars, but they are an instrumental part of winter bags. The collar should be fluffy enough to fill the excess space between your neck and shoulders, but not so bulky you feel like you are wearing an inner tube around your neck. Foot box. Since your feet take up room in the bottom of the bag, many sacks are designed with a flared, boxed, or barrel-shaped foot box to accommodate these protrusions better. In some mountaineering bags, extra room is added to the foot box to accommodate boots or water bottles.

Determine the Purpose of the Sleeping Bag

If being used for family camping--consider comfort
If backcountry camping--consider weight and size

What Type
Determine the Shape

Unless you are backpacking where weight is the overriding factor, you can choose whatever shape you like.

Sleeping bags come in either a rectangle, mummy or tapered shape, narrower at the bottom.

Rectangular Style Sleeping Bag

The most common sleeping bag is the rectangular style. It is roomy and comfortable inside, and can be opened and used as a comforter on warm nights.

If you like to sleep with your legs and arms all sprawled out, then a rectangular bag may be best for you.

 Many rectangular bags can be opened and zipped together to make a double size bag - great for very young kids and especially good for parents!

Generally, they are the least expensive and easiest to zip together to make a double bag for two people, but they are also the bulkiest and heaviest.

Rectangular type

Provides more space for movement
Can be zipped together to create a double sleeping bag
Can be fully opened and used as an extra blanket

Because of the extra space they are not as efficient in keeping you warm.
  Roll over in the middle of the night while sleeping and icy cold air can rush into the bag.  Further, you can move around at night and find yourself laying on a freezing cold part of the bag that hasn't had the benefit of your body warmth to keep that area comfortable. 

The casual, family or first-time camper often chooses a rectangular bag for its comfort and versatility.

Family camper's usually camp in the summer - 
therefore all you really need is this
basic rectangle Sleeping bag
 for cushion if anything else!

Some folks who are of very large frame like the rectangular bag so they can stretch out.
 Further, it is much easier to change your clothes inside a rectangular bag, where this can be a feat of acrobatics in a mummy style bag. 

Also if you're on a budget, bargains can be found looking at rectangular bags.

Mummy Style Sleeping Bag

The mummy style sleeping bag is meant to wrap tightly around the sleeper, so it will provide maximum warmth while using less material.
Mummy bags tend to be warmer because there is less space to heat.

 If you will be camping in cold weather, like 40 degrees and below, you might want to consider the mummy.
This efficiency will also keep the bag's weight to a minimum, they take up less room in a stuff bag making this style the choice if you will be backpacking.

Not everyone likes the confines of the mummy, so you might want to try one before buying.

Mummy type

Weighs less
Smaller size requires less energy to keep warm at night
Has a hood to pull tight around your head.

The more serious explorer, who needs protection in more extreme conditions, often prefers the efficiency and technical" features of the mummy design

Mummy bags are more expensive because they're more complex to make,
 but are worth it!

Tapered bags fall between the two.
They can be zipped to others with matching zippers, take less body heat to warm them than rectangular ones, and allow some room for foot movement.

Variations on these include the "barrel" shape, which is a mummy with extra space in the middle. This is a good compromise if you want a mummy's warmth but need a little space for comfort.

In a mummy bag the urgency of ones need to urinate is inversely proportional to the amount of clothing worn.
It is also inversely proportional to the temperature and the degree to which the mummy bag is completely zipped up.

Hybrid

Hybrid bags, also called tapers and semi-rectangular combine mummy bags with rectangular bags.  Resembling a rectangular bag, they may taper down slightly as they go toward the feet and will have a rounded end.  Like the mummy bag the removed space means lighter weight and less wasted area to keep warm at night.  Like a rectangular bag it offers more room for a person with a larger frame.  Usually weighing just a little more than a mummy bag, this style offers a good comprise between price, weight and warmth.

Overbags & Bivy Sacks

Overbags and Bivy Sacks are used with a sleeping bag.  Overbags are used when additional warmth is needed, like during extreme winter camping.  Overbags can also be used in extremely warm conditions as a light sleeping bag, when even the thinnest and lightest bag will roast you alive in hot humid conditions.  Overbags may also be used to supplement the waterproof abilities of a sleeping bag.  Bivy sacks are different.  Typically waterproof and made of a breathable material, a bivy sack is used when sleeping under the stars, in extreme wet conditions, or winter camping.  Both overbags and bivy sacks (you may hear these terms interchanged) increase the range of use of your bag, but cut down on how well the materials breathe.

Determine the Size

Sizes vary
Basic Sizes

Junior size bags are built for people up to 4'11" (59") tall

 The juniors are for small children. If weight is not important, I suggest you get a standard length for your child. The bag will last many years, and a junior size bag will soon be outgrown.

Full size bags (Standard) are most common and at a length of 6' 3" (75") fit most average-sized adults;

 
Tall size bags are the same width as a full but are longer 6' 5" (77") to accommodate taller individuals;
and 
King size bags are a little wider than the full bags and a little longer than tall bags, fitting most adults up to 6' 2" (74") tall.

Who will be using it?
An average sized person can fit comfortably inside most sleeping bags, but a small or a very large person needs to actually crawl inside one to be sure that it's long enough and wide enough for comfort and small enough to retain warmth.

A well-fitting bag will allow room to turn over and move around a little bit, but will not have so much air space that body heat won't warm it sufficiently.

A short person or a child might be able to get by with a normal sized sleeping bag by tying off the lower portion with twine or camping straps.

Another dimension to consider is the girth.
 Girth is the inside space, as measured around the sleeper's waist area.
Mummy bags have the smallest girth, and rectangular the largest.

Determine Temperature Rating

Depends on the conditions you plan to camp in
A bag temperature rating indicates the lowest temperature in which a person would be comfortable.

 "Comfortable" is a very subjective term
everyone is different 

Use of a ground pad is assumed, necessary and very important -
this provides extra insulation and comfort.
 A foam and air core pad is the best. 

 Other factors should be considered-
-quality of ground pad and tent, personal level of energy etc. 

Most bags are rated according to the lowest temperatures in which they provide comfort, but there is no set standard in the industry. The rating is determined by the manufacturer. A bag rated as "three season" means that it will be comfortable for sleeping for an average person in temperatures ranging from about 15º through the summer.

When selecting a temperature rating for a sleeping bag, be sure to consider the following:

The lower the rating, the warmer the bag

If you plan to camp in warm conditions and also want your bag to be comfortable on cool spring and fall nights, look for a three-season bag rated to 20 degrees

Traditional camp bags are comfortable to about 40 degrees

In general, consider the coldest night you will likely experience, and then drop down 10 or 20 degrees

Keep in mind that temperature ratings always assume that the bag will be used with a ground pad

The loft of a sleeping bag refers to how much the insulation "fluffs up"

More loft means more warmth

For maximum loft, look for a bag with a differential cut, one in which the inner lining is smaller than the outer shell. This allows the insulation to loft up to its maximum.

Basic ratings:

Traditional sleeping bags are rated at 40 degrees F
Three season bags are rated at 20 degrees F
Cold weather bags are rated at 0 degrees F
Winter camping bags are rated from -15 degrees F to -30 degrees F

Consider these as guidelines only. You may sleep warmer or cooler than someone else. These guidelines seem to assume that you will be wearing warm clothing too.
You can probably use any bag rated for summer temperatures as you start out, since you will most likely be camping during the warmer months.

There are several ways to make a bag warmer, other than wearing warmer pajamas. One common way is to use a "liner" bag. These bags are placed inside you regular sleeping bag, like adding an extra blanket to your bed. You can buy these bags ready made, or make one by attaching a blanket to the sleeping bag with safety pins. You can also just throw a blanket over the top of you bag, rather than put it inside. When it is really cold, two summer bags can be used, one inside the other.
You may also consider bringing the girth in by using the method described in the diagram above . . .

My suggestion
It's easy to make a sleeping bag warmer, so start with a warm weather bag like a 40 degree rating or warmer depending on your location.

Most people select three-season models thinking they represent the greatest value for the money.
Wrong!
The typical three season sleeping bag becomes too warm when temperatures rise above 50 degrees Fahrenheit, which means they are next to worthless for average summer use.

Only if you do considerable primitive camping in the spring and fall, should you buy a three-season bag. Otherwise, a lighter, less costly summer bag will be a better buy. Tent temperatures commonly run about 10 degrees warmer than the outside environment, so a good summer bag will keep you toasty well below freezing. In really cold weather, you can mate your summer bag with an outer or inner liner, or a blanket.

SHELL 

Nylon, Polyester, Taffeta: 

This is the most basic of materials and is used from bargain basement bags to custom made sacks.  The least durable of synthetic materials used on sleeping bags, these are best used for car camping or general walk-in camping.  Long journeys into the backcountry can test the limits of these materials.  Low cost and very breathable, nylon, polyester and taffeta are best used for late-spring, summer and early fall camping when conditions will be tepid to dry.  Although they breathe very well, without waterproof treating offer very little protection in damp conditions.

Ripstop: 

Ripstop is nylon or polyester that has had heavier threads woven into the material.  These heavier threads reinforce the shell making it stronger and a hair more moisture resistant  than nylon while still being very breathable.  Ripstop is an excellent choice for three season camping when things won't be too damp.

Microfiber, Gossamer Micro, DryClime:

Also made of nylon or polyester, microfiber and its cousin's gossamer micro and DryClime are very tightly woven fibers that are very strong and moisture resistant.  Because they do not have the heavier threads of ripstop, microfiber is softer than it's other counter parts.  Microfiber is an excellent choice for three season camping, or even four season camping if your winter camping is in ideal conditions and doesn't involve crawling into a snow cave for the night.

DryLoft: 

DryLoft is a close relative to Gore-Tex, but it is Gore-Tex with an attitude.  Sharing all of the water resistant abilities of Gore-Tex, DryLoft is very breathable, which means a more comfortable stay in your bag.  Just like your tent should allow moisture to get out, your sleeping bag should allow the natural perspiration breathe through the bag, and not get trapped inside, making for damp conditions by morning.  What that means is warm and dry on the inside, and damp and wet stays on the outside.  DryLoft is the premium choice for four season camping, canoe camping, or extended stays in the backcountry.

Gore-Tex:

Sleeping bags with a Gore-Tex shell should be avoided.  Although Gore-Tex is durable and water resistant, it doesn't breathe well which can make for damp conditions inside a bag.  Gore-Tex is an excellent choice when looking at an overbag or bivy sack to supplement your sleeping bag for winter camping or camping in extreme conditions.  Most manufacturers have stopped making sleeping bags with Gore-Tex shells.

Canvas:

If you go down to your Army Navy store you may find sleeping bags with canvas shells.  Canvas is very durable and breathable.  Canvas is made of cotton, and when it gets wet, it stays wet.  Also wet canvas is extremely heavy.  Canvas is also very heavy.  If you get a bag with a canvas shell, you probably will be using it for car camping.

Cotton:

Extremely breathable, lightweight, and easy to clean, cotton is a low cost material used in bargain bags.  Like canvas cotton does not take well to moisture, and due to it's ability to breathe and wick, should only be used in the warmest of conditions.

LINING 

Nylon, Polyester, Taffeta: 

This is the staple lining of sleeping bags.  Soft and supple, if you are using cotton blend sheets on your bed, you are already sleeping on the stuff.  Breathable and comfortable, these materials don't tend to heat up as much as others that can make lying in the same spot uncomfortably warm.  Lower cost bags may use nylon or polyester to making lining materials that feel like heavy sheets or a comforter.

Brushed or Fleece: 

Some sleeping bags may have a brushed lining or a fleece lining.  These bags help keep you feel warmer when the temperature slides down and it may feel better on your skin.  Fleece linings can trap heat, and if you tend to wake up when your pillow gets to warm these linings may have the same effect on you.

Silk:

When I became a winter survival school instructor I was issued a down mummy bag with a silk lining.  There is nothing like sleeping in a silk lined bag.  Soft, supple, breathable, and it doesn't overheat as you lay in the same spot.  Silk is very expensive and can tear more easily then other materials.  A tear in a silk bag is also very difficult to repair, and can be disastrous with a down filled bag.

Flannel or Cotton:

These natural materials are breathable, durable and lightweight.  They are also very easy to clean and repair.  Typically found in bargain bags, cotton and flannel both trap moisture, and should only be used in tepid conditions.

Determine Insulation

Once upon a time the good bags used prime goose down for insulation. This is still used, mainly in the highly specialized mountaineering bags where extreme dry cold, and light weight are the primary considerations. Down's cost and difficulty in washing make it impractical for most camping.

Actually, modern synthetics have been developed which have all but replaced down. Synthetics cost less, are washable, and can be nearly as warm as down, especially when it is damp outside. For most family camping situations, most any of the synthetics will be sufficient.

Down

Best natural insulator
Light and compressible
Must be kept dry
or it losses its insulating abilities
The best natural insulator, with a higher weight-to-warmth ratio than any synthetic on the market
The preferred choice for those who want to travel light in dry conditions
This insulation is more expensive than synthetic fills, and loses most of its insulating capacity when wet, plus it takes a long time to dry
Note that each down bag has a fill power number that indicates how much space an ounce of down will fill. The higher the power, the loftier and warmer the bag.

The type of fill (insulation) determines the amount of warmth that stays inside the bag; the warmth itself comes from the body heat of the person sleeping in it.

Goose down is a natural fiber that has long been held as the standard as lightweight, comfortable, and warm. They compact easily into small stuff bags, mold easily around a camper's body to retain heat, and are extremely durable. The down side is that they can be miserably uncomfortable if they get wet, take longer to dry, are more expensive than most synthetics, and are most safely cleaned professionally.

  Synthetic Fill

Cost less then down bags
Insulates even when wet
Dries quickly
ideal for boating trips and for camping in wet conditions 
Higher end synthetic fills come close to down's efficiency
They also weigh more than down and take up more space when packed
Among the most frequently used synthetic fills are Duofill and Hollofil

Synthetic fills provide enough warmth for most casual campers. Follow the manufacturer's guidelines for temperature rating, but adjust it according to your personal sleeping habits.
 If you know you are a cold sleeper, get one rated at a lower degree than you will be camping in.

Any sleeping bag can be made warmer by using a purchased or home-sewn flannel liner, and some bags come with their own

Determine the Lining

Nylon Taffeta
Used to line parts of the garment that are exposed to more abrasion than mesh can handle, or in areas where hydrophilic mesh would attract moisture from the outside such as the hem or cuff areas. This smooth, durable taffeta slips easily over mid-layers.
Polyester Cotton
Fleece

Some outer shells are moisture resistant; this is terrific at keeping out dampness, but they also can keep moisture in, resulting in a cold and clammy sleeping experience. If you perspire heavily, you may prefer a cotton exterior, or at least an absorbent interior fabric.

Some of the new materials will wick moisture to the outside without allowing it to penetrate in; they can add $100 to the price of a sleeping bag, but if you frequently camp in wet weather, it might be worth it.

Dark colors, both inside and outside, draw more heat from the sun. This is good on two counts: they dry out more quickly, and they stay warmer on cold, bright days.

PRICE

A good sleeping bag, intended for regular use during two or three seasons over a period of five or six years, will probably cost at least $80.

If you plan to camp for an entire summer, want your bag to last a lifetime, have allergies to some of the components, or need a very lightweight, very warm, water-wicking fabric, you can spend many hundreds of dollars.

Large, heavy, flannel-lined and canvas covered ones can be found for less than $50. These are fine for car camping during temperate seasons.

Consider Quality of Other Features

Seams and stitching
Zippers

Zippers should be of good quality, and should not pinch or catch on the fabric when zipping up. You should be able to zip it up from the outside or inside. If you plan to connect two bags together to make a double sleeping bag, make sure the zippers are compatible.

Some bags have a collar at the top that helps keep the opening closed around your neck to retain heat. This is useful in cold weather, but is unnecessary and perhaps annoying, in warm weather.

Hood

Rule number one in staying warm, 50% of your body's heat loss is through your head.  Unless you plan to only do summer camping, a sleeping bag with a hood is a must have option.  Hoods come in a variety of styles.  Some hoods are simply made of the shell material and stretch around your head.  Others may have drawstrings so you can cuddle up until just your face is coming through.  Others may be insulated and offer other features to help keep the rest of you warm.

Pocket

Some sleeping bags have zippered pockets or flaps on the outside of them.  These are handy for keeping things that are important close to you like eyeglasses, a small flashlight, or your watch (if you don't sleep with it on).

Compression Sack or Storage Bag

A storage bag helps protect your sleeping bag when it is not being used.  Usually made of a breathable material these bags allow you to pack your bag so that it is loose and this helps your loft maintain it's fill.  A compression sack is usually made of a more durable, moisture resistant material.  This is a special bag that allows you to squeeze down your bag, taking up less room in your pack.  Compression sacks are very important when hiking out in the backcountry but are not the best way to store your bag.  Long-term storage of a sleeping bag in a compression sack can make it loose its loft.

Draft Collar

A draft collar is usually found on mummy bags with hoods.  This insulated collar fits around your neck as you sleep.  Warm air stays in the bag, and cold air as you move around during the night stays out.

Zipper Draft Tube or Insulated Zipper

Usually hanging down over the zipper (which helps it stay in place) this baggy area over the zipper helps keep your body warmth in while keeping drafts through the zipper out.

CARE & STORAGE

Always open the bag after a night of sleeping in it to air it out. If it's not raining or damp out, spread it across the top of your tent or car for freshening.

 Don't toss the manufacturer's care instructions. 
Always read and follow them. Since fabrics and insulation differ, they might require different care. Most bags can be washed with a mild detergent (you can buy down-specific cleaning agents) in your bathtub or an industrial washing machine.
 Don't get your bag dry-cleaned.

Most sleeping bags are too large for most home washers. Take them to a Laundromat with jumbo sized equipment for laundering, or to a professional cleaning service. Goose down bags must be dry cleaned, then aired thoroughly before using again.

Synthetic fill usually air dries quickly on a clothesline or spread out on a flat surface. If it's safe for machine drying (check the tags!) toss a tennis shoe in with it to fluff it up.

Your sleeping bag will last longer if it's hung up, secured by clamps at the bottom end, when it's not in use. If you don't have adequate hanging space, leave it folded loosely, perhaps under a bed or on a shelf, between camping trips.

Consider a storage bag

Choosing a sleeping bag is really easy.
 In fact, you might not need a sleeping bag at all! 
Plenty of campers started and continue with a bedroll. You can make your own bedroll by taking sheets and blankets and making up a bed just like home. Add more blankets or a comforter for cooler weather.
It will be best if you have some sort of mattress to make your bedroll on, like a futon or air mattress.

Do's and don'ts  for sleeping bags Don't roll sleeping bags; stuff them! Don't yank sleeping bags out of stuff sacks; pull gently. Don't leave sleeping bags stuffed for long periods of time. Don't machine wash down sleeping bags. Don't  dryclean polyester filled sleeping bags. Don't wash down bags with harsh detergents. Don't pick up a wet down product without adequately supporting it. Do air and fluff sleeping bags after each use. Do store sleeping bags flat, on hangers, or in large porous sacks. Do sponge clean the shell of your sleeping bag occasionally. Do wash your sleeping bag when it gets dirty.

KEEPING COMFORTABLE 

Use a sleeping pad.
  Lying on the cold ground isn't going to help you stay warm in the middle of the night and it won't be comfortable either.

Go to the bathroom before getting into the sack.
  Anything sitting in your bladder will have to be kept at warm by your body as you sleep.

Use your hood on your sleeping bag.  
If your sleeping bag doesn't have a hood consider wearing a hat while sleeping.  Remember, 50% of your heat loss is through your head.

Wear clothes to bed. 
 If you are accustomed to sleeping in your underwear (or less) at night try sleeping in clothes.  You don't have to sleep in the pants and flannel shirt you wore during the day.  Long underwear or a pair of sweats can help keep you warm while taking up a relatively small amount of space and adding only a few ounces of weight to your pack.

Keep your bag dry. 
 Do everything possible.  Don't climb into your bag wet, especially if you are in an emergency situation and you think you are getting hypothermic.  A wet sleeping bag cannot keep you warm.  Also make sure that your tent is well ventilated so moisture does not build us as you sleep.  During the night you can expel over a cup of fluid.

Make sure your bag fits you. 
 If a bag is too small or too large it will create problems in staying warm.  A sleeping bag should fit you so that the insulation isn't squished up, but shouldn't have a lot of extra room.  A bag that is too large means you have wasted space to keep warm.  A bag that is too small simply cannot do its job of keeping you warm.

If you wakeup and find yourself cold try adding more clothes.  Eating some high calorie carbohydrates can throw some fuel on the internal fires.  If all else fails do some exercise to get circulation increased.  If you start shivering watch out for hypothermia and take increased steps to get warm including building a fire, drinking warm fluids and exercise.

"To keep warmer -
wear a hat to sleep in -
80% of heat loss occurs through your head."

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