Sleeping Bag Comfort vs Limit Temperature: How to ChooseThe Gap Is 4 to 8°C in 15 Official Bags

Choose a sleeping bag by matching its “comfort temperature” to the lowest temperature of the place you stay. The limit temperature is a number that assumes a person with high cold tolerance sleeping curled up inside. Among 15 bags where both are officially listed, the gap between the two was 4 to 8°C.

Sleeping bag comfort vs limit temperature: the basis for choosing is comfort temperature

Comfort temperature is the temperature at which you can sleep comfortably stretched out, and limit temperature is the temperature a person with high cold tolerance can sleep at curled up. A “0°C sleeping bag” is not a bag you can sleep comfortably in at 0°C.

The mont-bell Seamless Down Hugger 800 #3 has two temperatures on its official page: comfort temperature 5°C and usable temperature 0°C. The difference is 5°C.

In mont-bell's definition, 0°C was the temperature at which “a person with high metabolism and high cold tolerance” can sleep “curled up inside.”

Whose numbers are comfort (Comfort) and limit (Limit) temperatures?

The temperature is measured with a mannequin in underwear inside the sleeping bag, and in NANGA's explanation, placed on a mat. Cold from the floor is the mat's job, so read it together with the mat R-value guide. Comfort temperature is the temperature at which a person with low cold tolerance can sleep in a relaxed position.

Limit temperature is the temperature a person with high cold tolerance can sleep curled up inside the bag. NANGA describes the temperature range below that as “risk of hypothermia, extremely dangerous,” and mont-bell does not recommend use in the danger temperature range either.

Buy by the limit and you get a bag one rank colder

There is a trick to reading it. Shift mont-bell's numbers by one step. The #3's usable temperature is 0°C, the next warmer #2's comfort temperature is 1°C, and the other steps differ by only 1 to 2°C too.

A person who read it as “usable down to 0°C” and bought a #3 needs a #2 to sleep stretched out on a 0°C night, and the price difference of going up one number is JPY 2,000 to 7,800. Going through #7 to #0, lowering comfort temperature by 1°C averaged 37g and about JPY 1,395 (703 ÷ 19, 26,500 ÷ 19).

The names for comfort and limit temperature differ by maker

What is confusing is “usable temperature.” At mont-bell it means the limit temperature, with the paired comfort temperature written beside it, but ISUKA (minimum usable temperature) and Coleman (usable temperature on the Tasman Camping Mummy L-15, lower limit usable temperature on the L-8) give only the lower one, so I do not line them up beside other makers' comfort temperatures.

How I chose

The first thing I looked at was whether comfort temperature is the same as or lower than the lowest temperature of the place you stay. Next I compared weight and price within the same temperature band, and for those with the amount of down written, I also divided price per gram.

What I wavered on was around −5°C. By numbers alone, mont-bell's #0 is higher. I still made NANGA's 630DX my pick because you can confirm the amount of down officially.

Quick table of comfort and limit temperature: the gap is 4 to 8°C across 15 bags

Bags that officially list both comfort and limit temperature are 15 from 5 makers.

Scroll the table sideways →

The gap widens for winter models. At mont-bell it spread from 4°C at #7 to 7°C at #0, so for winter bags the misreading from buying by the limit temperature gets bigger.

Lowest temperature around 5°C: my pick is the mont-bell Seamless Down Hugger 800 #3

The comfort temperature is exactly 5°C and the weight 568g. Among four bags with nearby comfort temperatures, the price is second lowest and the weight second lightest. Only this one had both.

I do not rely on the usable temperature of 0°C. If the lowest temperature looks likely to drop below 3°C, add 200g and JPY 7,500 and go to the #2 from the start.

For low price, NEMO's Disco 30. But it is 880g. For lightness, the Spark -1C. It is light at 493g. But the price is about 2.2 times the #3's.

Lowest temperature around 0°C: my pick is the NANGA Aurora Tex Light 480DX

The deciding point is the share of down. The comfort usable temperature is exactly 0°C, and 55.2% of the weight is down. The gap between comfort and limit temperature is the largest of the 15, so if you read the −8°C on the tag as for winter mountains, you take it out on a night 8°C colder.

This part is a weak point. The price is about 1.5 times mont-bell's #2 and it is 102g heavier, so unless you want to confirm the amount of down in numbers, the #2 is enough.

Lowest temperature around −5°C: my pick is the NANGA Aurora Tex Light 630DX

There are only 3 candidates. Those that reach a −5°C night at comfort temperature among the 15 are this one, NANGA's 780DX and mont-bell's #0. The difference from the 480DX is 320g and JPY 12,100, and comfort temperature drops 6°C.

The weakness is price. mont-bell's #0 is JPY 17,100 lower, so this suits people who want to buy having confirmed the amount of down.

For low price, the Disco 15. JPY 49.7 per gram of down is the lowest of the 11 with the amount written, but it falls 2°C short of −5°C, so use it where the lowest temperature is down to −3°C.

How to read sleeping bags with no comfort temperature listed

ISUKA Air Plus 280

There is one number. The minimum usable temperature is −1°C and the weight 550g. The line is that if the lowest temperature is below this number, do not take it. People who cannot judge and beginners are safer choosing the warmer side of the guide, and it is not meant to be used right at the number. It suits people who can use it with margin in temperature.

Coleman Tasman Camping Mummy/L-15

There is only one temperature. The product page says “usable temperature: −15°C or above.” A Coleman reading page introduces the same model's comfort temperature as −9°C, a gap of 6°C.

It weighs about 3.4kg, a winter sleeping bag to carry by car, not on your back.

Who is it for?

It suits people whose current bag's comfort temperature does not reach the lowest temperature of the next place they stay. In the comfort temperature row of the table, choose one that is the same as or lower than the lowest temperature.

If you are short by just 2 to 3°C, you can adjust with insulated clothing or an inner sheet. If it is only summer lowlands, the #7 or Spark 7C with a comfort temperature of 11°C is plenty. If you are also thinking about heating the tent on winter nights, read the Captain Stag × Corona 50th anniversary oil stove review too.

mont-bell also writes that the temperature range is a test result and may differ from individual feel, so I did not use a 1 to 2°C difference between makers as material for choosing.

FAQ

Gear in this article

Ads & images: Rakuten Ichiba

mont-bell Seamless Down Hugger 800 #3Sea to Summit Spark -1CNANGA Aurora Tex Light 480DXNANGA Aurora Tex Light 630DXISUKA Air Plus 280Coleman Tasman Camping Mummy L-15

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