What R-value sleeping pad and bag rating do you need? Enter your expected overnight low and the advisor recommends a minimum pad R-value and a sleeping bag temperature rating — then checks whether your pads, stacked, actually meet it.
Find the sleeping pad R-value and bag temperature rating you need for a given overnight low — then check whether your pads make the grade.
Do your pads make it? (R-values add when stacked)
How this works & how to read bag ratings
Sleeping pad R-value by temperature
Recommended minimum R-value for the expected overnight low (R-value insulates you from the cold ground):
| Overnight low | Recommended R-value | Season |
|---|---|---|
| 60°F (16°C) | R 1.0 | Summer / warm nights |
| 50°F (10°C) | R 1.5 | Summer |
| 40°F (4°C) | R 2.5 | Three-season |
| 32°F (0°C) | R 3.0 | Three-season (freezing) |
| 20°F (-7°C) | R 4.0 | Late season |
| 10°F (-12°C) | R 5.0 | Light winter |
| 0°F (-18°C) | R 6.0 | Winter |
| -10°F (-23°C) | R 7.0 | Deep winter |
A guide for an average sleeper; cold sleepers should add ~0.5–1 R, and conditions like wind or wet ground call for more. Remember R-values add when you stack pads.
Sleeping bag temperature ratings (EN/ISO 23537)
Bags are lab-rated on a heated manikin. Choose by the Comfort rating and leave a buffer:
| EN/ISO rating | What it means |
|---|---|
| Comfort | The lowest temperature a cold sleeper stays comfortable. Choose by this rating — it suits most people. |
| Limit | The lowest temperature a warm sleeper, curled up, can sleep without shivering. For warm sleepers only. |
| Extreme | A survival threshold, not a usable temperature. Sleeping here risks hypothermia — never plan around it. |
How to build a warm sleep system
Staying warm at night takes two things working together: a sleeping bag (or quilt) rated for the air temperature, and a sleeping pad whose R-value insulates you from the ground. The ground conducts heat away far faster than air, so a warm bag on a thin pad still sleeps cold. For winter, stack a closed-cell foam pad under an air pad to add their R-values and gain puncture insurance. Down warmth is rated by fill power; a mummy bag traps heat best.
Frequently asked questions
What R-value sleeping pad do I need?
It depends on the coldest ground you’ll sleep on. As a guide: about R 1–2 for summer, R 3–4 for three-season use down to freezing, and R 5–6 or higher for winter and snow. Enter your expected overnight low in the calculator above for a specific recommendation; remember R-value insulates you from the cold ground, separate from how warm your sleeping bag is.
Can you stack sleeping pads to increase R-value?
Yes — R-values are approximately additive, so stacking pads combines their insulation. Putting a closed-cell foam pad (about R 2) under an inflatable pad (say R 4) gives roughly R 6, a common and reliable way to reach winter warmth. Stacking also adds puncture insurance, since the foam pad still insulates if the air pad fails.
What's the difference between the comfort and limit rating on a sleeping bag?
Under the EN/ISO 23537 standard, the Comfort rating is the lowest temperature at which a ‘cold sleeper’ stays comfortable, while the Limit rating is the lowest at which a ‘warm sleeper,’ curled up, can sleep without shivering. Most people — and especially cold sleepers — should choose a bag by its Comfort rating. The Extreme rating is a survival figure only and should never be used for planning.
Does the sleeping pad or the sleeping bag matter more for warmth?
Both matter, and they do different jobs. The sleeping bag insulates you from the cold air; the pad’s R-value insulates you from the cold ground, which conducts heat away far faster. A warm bag on a low-R pad still sleeps cold, so in cold conditions you must match both — the pad’s R-value to the ground and the bag’s rating to the air temperature.
How accurate are R-value and temperature ratings?
R-values are now standardized (ASTM F3340), so you can compare pads across brands reliably, and EN/ISO bag ratings are lab-measured on a heated manikin. But real nights vary with wind, humidity, your metabolism, clothing, food, and shelter, which can shift effective warmth by 10–15°F. Treat the recommendations as well-grounded starting points and leave a safety buffer.