Simond
Simond MT500 0°C synthetic trekking sleeping bag
Best use
- Made for
- Backpacking and wild camping
- Not for
- Bikepacking, Winter mountain
Why these labels
- Backpacking and wild camping: The maker states this use, and the published specs do not rule it out.
- Bikepacking: Bulky for bike bags: packs to 12.9 litres
- Winter mountain: Comfort rating 0 °C: too cold for winter nights
From the maker's stated use and the published specs.
- Summer wild camp: 4/10 UK, roughly May to September, nights above about 8 °C, sheltered pitches.
- Three-season hills: 5/10 UK hills in spring and autumn. Wind, rain, and nights near freezing.
- Winter camp: 4/10 UK winter or high ground. Below freezing, strong wind, possibly snow. Capped at 4: needs warmth 9+ (comfort -5 °C or colder).
- Weight: 4/10 How much it adds to your pack, compared with the whole market.
Comfort 0 °C, limit -5 °C (ISO 23537).
Cheap three-season wild camps and spring and autumn nights down to about 0 °C if you add a decent mat
- Zip
- Half
- Comfort
- 0 °C
- Limit
- -5 °C
- Fill
- synthetic
- Weight
- 1.45 kg (L)
Packed size 12.9 L, 39 cm long and 21 cm across Compare with a 2-litre bottle
A bit longer than a 2-litre bottle and about twice as wide. Drawn to scale.
Where to buy
Decathlon UK £69.99 In stock. Delivery from £2.99.
View at shop: Decathlon UKPrices checked 8 Nov 2026 on each shop's own page; shops can change them. We earn no commission on these links; shops are listed by price. More
Our ratings (out of 10)
1 to 10, compared with the whole market. Each says what it's based on. How we score
Warmth
From maker's figures 7/10How cold a night you can sleep comfortably through. 7: Better than most.
Decathlon UK states the comfort temperature is lab-tested to ISO 23537-1:2022: comfort 0 °C (limit -5 °C), which sits in the -4.9 to 0 °C band. The maker's figure, not re-tested.
Room inside
Estimate from maker's specs: bag shape (fewer than 3 reviews about room) 3/10How much room to move, bend your knees and sleep on your side. Roomier is comfier. 3: Below average. Fine for some trips, not others.
No review we found says how roomy it is, so this is an estimate from the bag shape.
Weight
From maker's figures 4/10How much it adds to your pack. 4: A bit below average.
1,450 g for size L sits in the 1,300-1,699 g band.
Packed size
From maker's figures 3/10How much room it takes in your rucksack. 3: Below average. Fine for some trips, not others.
Decathlon states 12.9 L for size L, in the 9-12.9 L band, so the maker's litres are used. Working the 39 x 21 cm roll as a cylinder gives 3.1416 x 10.5 x 10.5 x 39 = 13,507 cm3, about 13.5 L, which would be the 13 L+ band, so treat it as the top edge of its band.
What reviewers say (out of 10)
Ratings marked * are from reviews and are not part of the trip score. They are reviewers' scores, not our own measurements. How we score
Comfort to sleep in*
Estimate: only 2 reviews about comfort to sleep in (fewer than the 3 we need, so never above 8) 8/10How comfy the shape, hood and fabric feel; not the temperature rating.
2 reviews on comfort to sleep in, e.g. "that's just a great synthetic sleeping bag with a comfortable shape and very few compromises".
Zip*
Estimate: only 2 reviews about zip (fewer than the 3 we need, so never above 8) 6/10How smoothly the zip runs without snagging.
2 reviews on zip, e.g. "They're not the best zippers ever, but they do the job.".
In short
Good for
- Cheap three-season wild camps and spring and autumn nights down to about 0 °C if you add a decent mat
- Campers who want a synthetic bag that keeps working when it gets damp
Strengths
- Synthetic fill, so a damp night is less of a worry than with ordinary down
- Customers rate it highly on Decathlon UK, and a few say it was too warm to keep fully zipped at around 0 °C
- Water-repellent outer fabric, 3/4-length zip with snag guard and a draught tube along the zip
- Comes in four sizes (S to XL), with a 5-year Decathlon warranty
Weaknesses
- Heavy and bulky for trekking: size L is 1,450 g and packs to about 13 L, so it takes up a lot of a rucksack
- Customers and the owner reviewer both call it big when packed, and the owner thinks 1.4 kg is too heavy
- Comfort 0 °C is the maker's figure for a standard woman on a very warm mat (R 4.8): cold sleepers should expect to need layers and a good mat near freezing
- Short on independent evidence: we found no magazine or specialist test of this exact 0 °C bag (the owner video is of an earlier Forclaz-branded version), so damp performance, comfort and durability are estimates, not reviewed scores
- Small sizes run tight: one UK buyer who ordered a size too small compared it to a coffin
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.
ShowHide sources (4)
- Decathlon UK: Simond 0°C trekking sleeping bag MT500 (spec page: ISO 23537-1:2022 statement, sizes, weight, volume, price)
- Decathlon UK customer reviews: 0°C trekking sleeping bag MT500 (810 reviews, 4.65 out of 5; first page of 81 read)
- Camper Herd (Manada Campista): Sleeping bag MT 500 de Forclaz, buena opcion para acampar? (video, Spanish; auto-captions read)
- Belgian Hikers (YouTube): Watch this before buying a Decathlon hiking sleeping bag! (Simond MT900 down and the 0°C MT500 synthetic, 1,450 g, 12.9 L, labelled Forclaz)