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Sleeping Bag Calculator

Get the right temp rating for comfortable sleep

Temp Rating

25°F

Comfort

35°F

Fill

Synthetic

Recommended Temp Rating

25°F

3-Season

Comfort

35°

Rated

25°

Survival

10°

Recommendations

Fill TypeSynthetic or Down
Bag ShapeMummy or Semi-Rectangular

Example Calculations

13-season, average sleeper, 5000 ft

Inputs

Season3-Season
Sleep StyleAverage
Altitude5,000 ft
Pad R-Value3

Result

Temp Rating25°F

Base 25°F + 0°F style + 0°F altitude - 0°F pad = 25°F.

2Winter, cold sleeper, 10000 ft

Inputs

SeasonWinter
Sleep StyleCold
Altitude10,000 ft
Pad R-Value5

Result

Temp Rating-11°F

Base 10°F - 10°F cold - 17.5°F altitude + 6°F pad = -11.5°F.

Frequently Asked Questions

Q

What temperature rating sleeping bag do I need?

Choose a bag rated 10–15°F below the lowest temperature you expect. For 3-season camping (30–50°F lows), a 20–30°F bag is ideal.

  • Summer (50°F+ lows): 35–50°F bag
  • 3-season (30–50°F): 20–35°F bag
  • Winter (0–30°F): 0–15°F bag
  • Expedition (<0°F): -20°F or lower
SeasonTemp RatingFillWeight
Summer35°FSynthetic1–2 lbs
3-Season20°FDown 650FP2–3 lbs
Winter0°FDown 800FP3–4 lbs
Q

Does sleeping pad R-value matter for warmth?

Yes, significantly. Your sleeping pad insulates you from ground cold. Each R-value point above 3 effectively adds about 3°F of warmth to your sleeping system.

  • R-value 1–2: summer only, minimal insulation
  • R-value 3–4: 3-season, good insulation
  • R-value 5+: winter-rated, excellent insulation
  • Higher R-value = warmer sleep system
Q

Do cold sleepers need a warmer bag?

Yes. Cold sleepers should subtract 10°F from the standard rating. If a 20°F bag would normally work, a cold sleeper should get a 10°F bag.

  • Warm sleeper: +10°F comfort bonus
  • Average sleeper: use rated temp
  • Cold sleeper: -10°F, need warmer bag
  • Women often sleep colder than men
Q

How does altitude affect sleeping bag needs?

Temperature drops roughly 3.5°F per 1,000 feet above 5,000 feet. At 10,000 feet, expect it to be 17°F colder than at sea level.

  • 5,000 ft: no significant adjustment
  • 8,000 ft: ~10°F colder than sea level
  • 10,000 ft: ~17°F colder
  • 14,000 ft: ~31°F colder

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Last Updated: Mar 20, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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