What is R-value?

Ask us which pad is warmer and we'll answer with one number. R-value tells you how much a sleeping pad resists the cold ground — here's what it means and how to use it when you pick your next pad.

Heat goes down, not up

At night your body loses heat in every direction, but the ground is the biggest thief, because it's cold, it's dense and it touches you all night. Your sleeping bag's insulation under you is crushed flat by your weight, so the pad has to do the work.

How R-value is tested

R-value is thermal resistance. Pad makers test it under the ASTM F3340 standard: a pad sits between a warm plate and a cold plate, and the lab measures how much energy it takes to keep the warm side warm. The more resistance, the higher the number — and because everyone tests the same way, R-values compare cleanly between brands.

Which number do you need?

What R-value do I need?

Summer and warm-weather trips: 1 to 3. Our NeoAir Venture (2.2) and Z Lite SOL (2.0) live here.

Three seasons with cold mornings: 3 to 5. The Trail ProLite (3.8), Trail Pro (4.4), XLite NXT (4.5) and NeoLoft (4.7) cover this range.

Winter and snow: 5.5 and up. The BaseCamp and LuxuryMap (6), MondoKing 3D (7.0) and NeoAir XTherm NXT (7.3) are built for it.

Stacking pads

Do R-values add up?

Yes. Put a Z Lite SOL (2.0) under an XLite NXT (4.5) and you sleep on about 6.5 — warm enough for snow camping — while the foam also protects the air pad from sharp ice and rock.

R-value isn't everything

Cold sleepers may want more than the guideline, and a pad is only part of the system: a sleeping bag or quilt with the right temperature rating, dry base layers and a hat matter too. But if your hips feel cold at 3 a.m., the pad is usually where to start.