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01 — Camp / Guide

What R-value sleeping pad do I need?

R-value is the one sleeping-gear number that is tested to a published standard. It is also the number that decides whether your bag rating means anything.

By Brijon M.Last updated How we pick
An inflatable sleeping pad and bag laid out inside a tent

The short answer

For summer use, R-value 2 or above. For three-season camping down to around freezing, aim for R-value 3 to 4. For nights in the 20s Fahrenheit, 4 to 5. For sustained winter and snow, 5.5 and up, or stack two pads -- R-values add.

01 — The number

What R-value actually measures

R-value measures resistance to heat flowing through the pad. A higher number means less of your body heat is conducted into the ground over the course of a night. That is all it measures -- not comfort, not thickness, not how well it works on a cot.

It matters more than most people expect because conduction into the ground is a far more efficient route for heat loss than convection into the air. You can be in a bag rated well below the overnight temperature and still be cold, every time, because the pad under you is the actual problem. This is the single most common cold-sleeping complaint and the single easiest one to fix.

Since 2020 there has been an industry test standard, ASTM F3340, and the major brands publish figures measured to it. That makes R-values comparable across brands in a way that almost no other outdoor spec is. If a pad quotes a vague four-season claim instead of a number, that is information too.

02 — The chart

R-value by overnight low

Pick by the temperature you will actually see, not the temperature you hope for. These bands assume a bag or quilt appropriate to the same conditions and a tent rather than open ground.

Overnight lowR-value to aim forTypical useWhat it looks like
Above 60F1.0 - 2.0Summer, warm nightsA thin foam pad or a basic air pad
40F to 60F2.0 - 3.0Summer and early fallMost entry-level inflatables
30F to 40F3.0 - 4.0Three-season, most of the yearA standard insulated inflatable
20F to 30F4.0 - 5.0Late fall, high elevationAn all-season inflatable
0F to 20F5.0 - 6.5Winter campingAll-season inflatable plus a foam pad
Below 0F6.5+Snow and expeditionStacked pads, always

03 — Stacking

R-values add, which is the useful part

Put two pads on top of each other and their R-values add. A closed-cell foam pad at R 2.0 under an inflatable at R 4.2 gives you about 6.2, which is a genuine winter sleeping system assembled from two things you may already own.

This is worth knowing before you spend on a dedicated winter pad. Stacking also buys you redundancy: the foam pad cannot puncture, so if the inflatable fails at 2am in February you still have something between you and the snow. That is why most winter campers carry both rather than one very good pad.

The order matters a little. Foam underneath, inflatable on top, is the usual arrangement -- it protects the inflatable from whatever is on the ground and puts the more comfortable surface against you.

What R-value do I need for 20 degree weather?

Around 4 to 5. A single all-season inflatable covers this, as does a three-season pad with a foam pad underneath. At this temperature the pad is usually the limiting factor rather than the bag, because most people own a bag rated lower than their pad is insulated.

What R-value do I need for winter and snow?

At least 5.5, and most winter campers run 6 or above by stacking. Snow is an excellent conductor and it is also wet, which is a second reason to have closed-cell foam at the bottom of the stack. Best sleeping pads has the full field, and the rest of the kit is in winter camping gear list.

Does R-value matter on a cot?

More than you would think, and in the opposite direction from what people expect. A cot puts you in moving air, so in cold weather a cot is colder than the ground unless you insulate the cot surface. Put a pad on top of it. See best camping cots.

04 — Caveats

Where the number stops being the whole story

R-value is reliable, but four things sit outside it and all four affect how warm a night actually is.

  • Thickness and shape decide comfort, not warmth. A 3-inch pad at R 4 and a 1-inch pad at R 4 insulate the same and feel completely different.
  • Width matters for warmth indirectly: an arm or a hip hanging off the edge of a 20-inch pad is in direct contact with the ground.
  • Sleeping style changes the effective rating. Side sleepers compress the insulation under the hip and shoulder, which reduces the R-value exactly where the pressure is.
  • A bag's temperature rating is measured with a pad underneath. Without one, the rating does not apply at all -- the loft under you is crushed flat and does nothing.
  • Wet insulation is worse insulation. A pad on a tent floor with condensation on it is not performing at its rated value.
  • Older pads predate ASTM F3340. Figures published before 2020 are often optimistic and are not comparable with current ones.

05 — Buying

How to buy once instead of twice

The common mistake is buying for the trip in front of you rather than for the coldest trip you will take in the next few years. An R 2 pad bought for July is a pad you replace in October.

The efficient purchase for most people is a single inflatable in the R 4 to 5 range plus a cheap foam pad. That combination covers summer (inflatable alone), three seasons (inflatable alone), and winter (both), for less than a dedicated winter pad costs. Comfort differences are covered in sleeping pad vs air mattress, and the car-camping case, where weight stops mattering, is in best car camping mattresses.

What to buy

The gear we would buy for this

Trail & Terminal earns a commission when you buy through our Amazon links, at no extra cost to you. It does not change which products we pick -- see our affiliate disclosure and selection method.

1

Best for the bottom of a stack, and summer alone

Therm-a-Rest Z Lite Sol

R 2.0 of foam that cannot fail. The cheapest way to add insulation to anything else you already own.

Buy this first even if you are also buying an inflatable. It is the piece that makes the rest of the system flexible: summer sit pad, winter base layer under the air pad, and a spare if anything springs a leak.

It is also the cheapest honest answer to a cold night. Most people who report being cold on an R 3 pad are fixed completely by putting this underneath it.

Specs

  • Closed-cell foam, accordion fold
  • R-value around 2.0
  • About 14 oz, regular length
  • Reflective face

Good for

  • Adds its full R-value to any pad you put it under
  • Cannot puncture, so it is the redundancy in a winter system
  • Cheap enough to own regardless of what else you buy

Bad at

  • Firm and thin -- comfort is the price of indestructibility
  • Bulky folded; it straps to the outside of a pack
  • R 2.0 alone is summer only
2

Best for three-season backpacking

Therm-a-Rest NeoAir XLite NXT

R 4.5 at under a pound. The pad most backpackers settle on and keep.

If you are buying one pad and carrying it on your back, this is the default. R 4.5 is the point where the pad stops being the limiting factor in a three-season kit, and the weight is low enough that there is no argument for anything thinner.

Add a foam pad underneath for winter and the stack lands near R 6.5. That is the single-purchase path to a year-round sleeping system -- see <a href="/camp/winter-camping-gear-list">winter camping gear list</a> for the rest of it.

Specs

  • ASTM-tested R-value around 4.5
  • Roughly 13 oz in the regular size
  • 3 inches thick
  • Pump sack included

Good for

  • Covers everything from summer to light winter in one pad
  • Packs to about the size of a 1L bottle
  • The reflective internal layers do real work rather than marketing work

Bad at

  • Audibly crinkly, which some people cannot get past
  • Expensive for the size
  • Inflatable -- carry the patch kit, every time
3

Best for cold sleepers and shoulder-season trips

NEMO Tensor All-Season

R 5.4 and noticeably quieter than most high-R inflatables. The pad for people who are always cold.

The case for buying above R 5 in a single pad is that you sleep cold, or that most of your trips are at elevation or outside summer. Both are common enough that this tier exists.

If neither applies, the XLite plus a foam pad gets you to the same place for less money and more flexibility. Buy this when you want one pad and no stack.

Specs

  • ASTM-tested R-value around 5.4
  • 3 inches thick
  • Internal suspension reduces crinkle
  • Pump sack included

Good for

  • Enough insulation for genuine late-season and light winter use
  • Quiet, which matters more than the spec sheet suggests
  • Stable edges for side sleepers

Bad at

  • Heavier and pricier than a three-season pad
  • Overkill for summer -- you will be too warm
  • Still inflatable, with everything that implies
4

Best for car camping, where weight is irrelevant

Exped MegaMat 10

R 8.1 and four inches of foam. Heavy, enormous packed, and the most comfortable thing here by a distance.

Included to mark the top of the range and to make a point: once you are car camping, R-value stops being a constraint and comfort takes over entirely. Nobody carries this, and nobody who has one is cold.

If this is where you are shopping, the comparison that matters is against a true air mattress rather than against backpacking pads -- see <a href="/road-trip/best-car-camping-mattresses">best car camping mattresses</a>.

Specs

  • R-value around 8.1
  • 4 inches thick, self-inflating foam core
  • Several pounds and a large packed size
  • Flat valves, inflates mostly on its own

Good for

  • More insulation than any realistic car-camping night needs
  • Comfort genuinely comparable to a bed
  • Self-inflating, so setup is opening a valve and waiting

Bad at

  • Far too heavy and bulky to carry anywhere
  • Expensive
  • Takes a large share of the trunk

Questions

Frequently asked

What R-value sleeping pad do I need?
Match it to the overnight low: R 2 for summer, R 3 to 4 for three-season use down to freezing, R 4 to 5 for nights in the 20s, and R 5.5 or more for winter. Stacking two pads adds their values together.
Do sleeping pad R-values add up when you stack them?
Yes. A foam pad at R 2 under an inflatable at R 4.5 gives roughly R 6.5. Stacking is the cheapest way to reach winter insulation and it gives you a backup if the inflatable punctures.
What R-value do I need for 20 degree weather?
Between 4 and 5. One all-season inflatable covers it, or a three-season pad with a closed-cell foam pad underneath. At this temperature the pad is usually the weak link rather than the sleeping bag.
Is R-value tested the same way by every brand?
Since 2020, largely yes. ASTM F3340 gives a common test method, and the major brands publish to it. Figures from before 2020 or from brands that quote season ratings instead of numbers are not comparable.
Does a higher R-value make a pad too hot in summer?
Slightly, but it is rarely the problem people expect. Excess insulation underneath is easier to manage than too little -- you can vent the bag. Most summer discomfort comes from air temperature, not from the pad.

References

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