DownTo1 Packs

The engine's answer

Best side sleepers sleeping mat in winter nights near −12 °C, under €700

Sea to Summit

Ether Light XT Extreme

Ten centimetres of air with a winter R-value underneath it.

  • High R-value with unusual thickness
  • Excellent for side sleepers in cold conditions
  • Quiet, non-crinkly fabric
  • Heavy and expensive
  • Takes a while to inflate fully

Find it at Bergfreunde · Trekkinn · Decathlon · Alpinetrek · eBay (used)

Why it wins, in numbers

Sea to Summit Ether Light XT Extreme is the sleeping mat the engine picked for this trip: €260 and 700 g, R-value 6.2, a 93% match on the questions asked. The kit around it comes to €665 of the €700 ceiling, leaving €35.

What the engine asked for: a sleeping bag rated to −14 °C or lower, a mat with an R-value of at least 5.5, a pack of at least 41 L, and €700 for all four; anything that falls short of these is flagged beside the item.

The kit it belongs to

Four items chosen together, not four separate winners. Swapping one moves the others.

3.70 kg on your back · €665 of a budget of €700

Tent
3F UL Gear Lanshan 2: €130, 1.10 kg, Season rating 3, 50% match.
Sleeping bag
Forclaz MT100 15 °C: €35, 800 g, Comfort rating 15 °C, 28% match. Flagged: Not warm enough for these nights.
Sleeping mat
Sea to Summit Ether Light XT Extreme: €260, 700 g, R-value 6.2, 93% match. Strongest on: Sleep style.
Backpack
Osprey Exos 48: €240, 1.10 kg, Capacity 48 L, 50% match.

What the runners-up gave up

Each of these still leaves a kit that closes — the budget holds and the pack shuts. This is where each one lost.

  • Robens PrimaCore 90A thick, warm self-inflating mat for people who have given up on grams.Robens PrimaCore 90 — €130, 1.10 kg — gives up Weight: 1.10 kg against the winner's 700 g. It scores 92% to the winner's 93%.
  • Nemo Tensor Extreme ConditionsThe warmest mat here, for ground that is genuinely frozen.Nemo Tensor Extreme Conditions — €280, 640 g — gives up Thickness: 8.9 cm against the winner's 10.0 cm. It scores 83% to the winner's 93%.
  • Exped Ultra 7RSnow-camping warmth without a foam mat underneath.Exped Ultra 7R — €260, 730 g — gives up Thickness: 7.0 cm against the winner's 10.0 cm. It scores 69% to the winner's 93%.

Questions this trip raises

How much does the whole kit cost?
€665 for all four items, €35 under the €700 ceiling. Prices are indicative euro list prices; the shops set their own.
How much does it weigh?
3.70 kg base weight — tent, sleeping bag, mat and pack together, before food, water and clothes. The pack is rated to carry 16 kg comfortably.
Is Sea to Summit Ether Light XT Extreme warm enough on the ground at −12 °C?
Its R-value is 6.2. For nights near −12 °C the engine requires at least 5.5, which it meets.

Change an assumption

This page answers one trip. Yours is not that trip — adjust the nights, the budget or the company and watch all four re-rank.

Build my kit

Specifications are manufacturers’ own published figures and prices are indicative, not live. Comfort ratings and R-values are comparable across brands but describe a standardised sleeper on standardised ground — neither is a promise about you on a particular night. Check the current spec and price with the retailer before buying.