How To Buy a Sleeping Bag

Some of the most cathar­tic moments you expe­ri­ence dur­ing mul­ti-day wilder­ness escapes hap­pen when you slip into your sleep­ing bag beneath the stars. The bliss­ful warmth that engulfs your sore body as you lie your head down sim­ply can­not be repli­cat­ed with Egypt­ian cot­ton sheets. But that’s only if you bring the right sleep­ing bag. If you don’t, you run the risk of spend­ing the night in mis­ery, strug­gling like a fish out of water—a thrash­ing, shiv­er­ing dis­as­ter. The dif­fer­ence between com­fort and mis­ery out­doors comes down to mak­ing the right buy­ing deci­sion. Here are a few point­ers to help you choose the best sleep­ing bag for your needs.

Tem­per­a­ture Rat­ings: Sleep­ing bags are broad­ly cat­e­go­rized by tem­per­a­ture rat­ing, mean­ing the tem­per­a­ture list­ed is the cold­est that your bag can han­dle com­fort­ably. Be sure to check if the tem­per­a­ture rat­ing fol­lows the EN 1357 stan­dard, which is used by many com­pa­nies to pro­vide uni­form ratings.

If the tem­per­a­ture rat­ing is not based on EN 1357, it might be an arbi­trary des­ig­na­tion by the com­pa­ny that you may or may not agree with. Even if the EN 1357 stan­dard is fol­lowed, tem­per­a­ture rat­ings are sub­jec­tive. While one per­son may sleep com­fort­ably in a 20-degree bag at 10 degrees, anoth­er may freeze in the same bag at 30 degrees.

If you get cold eas­i­ly or have sweaty hot flash­es all night, you will want to keep in mind that these rat­ings are based on aver­age com­fort lev­els. Wet/humid cli­mates tend to feel cold­er (when it’s cold) and hot­ter (when it’s hot) then the same tem­per­a­ture in dry cli­mates. Also keep in mind that the rat­ings are based on the user wear­ing a sim­ple base lay­er. The tem­per­a­ture range of a bag can be extend­ed by wear­ing heavy cloth­ing inside the bag.


Sea­son rat­ings: Addi­tion­al­ly, some sleep­ing bags have a sea­son rat­ing in addi­tion to the tem­per­a­ture rat­ing to give you an idea of its best use.

Sum­mer bags: Should not be used where the tem­per­a­ture dips below freezing.
Three-Sea­son bags: Can some­times han­dle below-freez­ing tem­per­a­tures, but noth­ing too frigid.
Win­ter bags: These are excel­lent for keep­ing warm when there is a bliz­zard out­side your tent, but not ide­al for oth­er sea­sons unless used as a blanket.
Extreme bags: For when it’s real­ly cold. For exam­ple: high in the Himalayas or on an ice sheet in Antarctica.

Weight: The weight of your bag depends large­ly on what type of mate­r­i­al it is filled with (more on that lat­er). Addi­tion­al­ly, you will be sac­ri­fic­ing weight for space. Roomi­er bags are heav­ier than their form-fit­ting counterpart.

If you are car camp­ing, weight might not be an issue. How­ev­er if you’re going on an extend­ed back­pack­ing trip, then you’ll want the light­est bag com­fort­ably possible.


Insu­la­tion Type: The mate­r­i­al inside the bag used to keep you warm is called fill. There are three main types of fill:  Down, Syn­thet­ic, and Cotton.

Down: Made from the under­coat­ing of young birds, this nat­ur­al mate­r­i­al is a fan­tas­tic insu­la­tor. It’s light­weight, com­press­ible, and retains vol­ume after get­ting packed and repacked many times.  How­ev­er, it does have some drawbacks:

    • It is more expen­sive than syn­thet­ic fill
    • Los­es abil­i­ty to insu­late when wet (Water resis­tant down com­bats this to an extent)
    • Takes a long time to dry when wet
    • Requires a depen­dence on farm­ing waterfowl

Water resis­tant down: Tech­nolo­gies like Dri­D­own (unique to Sier­ra Designs) and Down­Tek (a third-par­ty sup­pli­er of water resis­tant down) treat down in a way that makes down more apt to wet cli­mates. While a great inno­va­tion, it is more expensive.

Syn­thet­ic fill: Syn­thet­ic down is intend­ed to copy the effects of down.  It’s usu­al­ly made from poly­ester fibers and is a great alter­na­tive if price is a fac­tor. Addi­tion­al­ly they work much bet­ter in wet envi­ron­ments, dry­ing out faster and repelling water instead of absorb­ing it.  How­ev­er, syn­thet­ic fill does not pack well and has a high­er weight-to-warmth ratio than a down bag with the same tem­per­a­ture rating.

Cot­ton fill: Cot­ton is a poor option. Cot­ton doesn’t have any prop­er­ties that make it supe­ri­or to the oth­er two options except for price. It’s a poor insu­la­tor, does not pack well, and is dread­ful­ly sog­gy when wet.

Fill Pow­er: Not all down is cre­at­ed equal, and fill pow­er helps you make a bet­ter deci­sion based on your weight/volume expec­ta­tions. The high­er the fill rat­ing, the lighter and more com­press­ible your bag will be com­pared to one with a low­er fill rat­ing of equal temperature/warmth.

Over time, the fill pow­er can decrease.  Wash­ing your bag, espe­cial­ly with a few ten­nis balls, will help “fluff” the bag and bring the fill pow­er back.


Shape: There are three main shapes for sleep­ing bags: rec­tan­gu­lar, mum­my, and hybrid. While large­ly per­son­al pref­er­ence, the shape also deter­mines how well the bag can recir­cu­late body heat.

Rec­tan­gu­lar bags: Shaped just as the name implies. They are roomy, which in sleep­ing bag speak, also means bulky. Gen­er­al­ly they zip all the way to the feet and can even be opened up to use as a blan­ket mak­ing them great for sum­mer.  Some bags can even be zipped togeth­er for mul­ti­ple bod­ies to share body warmth.

Mum­my bags: These are tapered at the feet, and often­times include a hood, mak­ing mum­my bags a bet­ter insu­la­tor than a rec­tan­gu­lar bag. How­ev­er some­times it works too well and since zip­pers usu­al­ly only goes halfway down the body, ven­ti­lat­ing on warm nights can be a has­sle for warm sleep­ers. On the oth­er hand, the small­er vol­ume of a mum­my bag saves on weight mak­ing them more compactable.

Hybrid bags: Hybrids are a com­pro­mise between rec­tan­gu­lar and mum­my bags. They pro­vide the roomi­ness and ven­ti­la­tion of a rec­tan­gu­lar bag, but are lighter and more pack­able and have a hood for cold nights.

Women spe­cif­ic bags: Women spe­cif­ic bags have wider seams at the chest and hip. Many com­pa­nies make women spe­cif­ic bags.


Pack­a­bil­i­ty: A warm, roomy sleep­ing bag is not much use if it doesn’t fit in your back­pack. Sim­i­lar­ly, if space is not an issue (i.e. if car camp­ing), then get­ting an expen­sive bag sim­ply because it packs up small might not be the best use of your resources.

Packed Vol­ume:  Some bags pack more tight­ly than oth­ers, which is impor­tant when you have lim­it­ed space in your back­pack.  Packed vol­ume is a met­ric that helps gauge the size of your bag when packed. Most sleep­ing bag mod­els will pro­vide this, or the infor­ma­tion can be found with a lit­tle bit of inquiry.

Con­tain­ment: When pack­ing your bag, there are usu­al­ly two options to con­tain it: A stuff sack or com­pres­sion sack. Cot­ton bags don’t real­ly apply here since they are made to “fold and roll”.

Stuff Sacks: Stuff sacks allow you to quick­ly and eas­i­ly “stuff” your bag into the sack with lit­tle regard for order. This is a good way to store your down bag, as it gives the down room to retain its shape over time. Pro tip: if down com­pressed for too long then it can take a long time for it to get it’s “fluffi­ness” back.

Com­pres­sion Sacks: These can be cinched down and get the bag com­pressed to its small­est pos­si­ble vol­ume, giv­ing you extra room in your pack for oth­er fun sup­plies. Many com­pres­sion sacks are water­proof. Keep in mind that down bags shouldn’t stay in com­pres­sion sacks after the trans­port. Opt for a more volu­mi­nous sack when being stored.

With so many vari­ables, find­ing the right sleep­ing bag can seem daunt­ing. Often times the ide­al bag is dic­tat­ed by the price tag. But keep in mind that if you take care of your sleep­ing bag, it can last for many adven­tur­ous years. One day, slip­ping into your sleep­ing bag at the end of a hard slogged day in the ele­ments, and you’ll be glad you did your homework.