The Kelty Mistral 40 is the lightest and simplest model in the Mistral line — a synthetic mummy bag with CloudLoft insulation rated by the manufacturer to a 4°C limit, aimed at summer nights and lower elevations. Unlike its siblings the Mistral 0 and 20, it skips recycled materials and DWR treatment, and the zipper is one-way only with no draft collar — this is the entry-level, budget option in the range.
At 1300 g total with 830 g of fill, its warmth-to-weight ratio of 3.1 is below average for this group, reflecting the simpler sewn-through baffle construction. Shell and liner are both 190T polyester taffeta; a draft tube along the right-side zipper is retained even without the collar, and an internal pocket and stuff sack are included. Internal length is 193 cm, maximum user height 183 cm, packing to 41 x 23 cm.
For summer camping and budget-conscious autumn weekend trips, the Mistral 40 is a functional choice — but the lack of DWR treatment is a real limitation on trips with meaningful rain or moisture risk.
Specifications
Limit Temperature
4 °C
Temperature Rating Standard
Manufacturer rated
Season Rating
3-season
Total Weight
1300 g (2.87 lb)
Fill Weight
830 g (1.83 lb)
Internal Length
193 cm (6.3 ft)
Packed Size ( Length x Diameter )
41 x 23 (1.3 x 9.1 ft)
Insulation Type
Synthetic
Synthetic Insulation Name
CloudLoft
Shape
Mummy
Baffle Construction
Sewn-through
Zipper Side
Right
Zipper Length
Full length
Shell Fabric
190T Polyester Taffeta
Liner Fabric
190T Polyester Taffeta
Water Resistance
None
Draft Tube
✓
Internal Pocket
✓
Stuff Sack Included
✓
Size Category
Regular
Maximum User Height
183 cm (6.0 ft)
Gender-Specific Fit
Unisex
Warmth-to-Weight Ratio f(x)
3.1 °C/kg
Fill Efficiency f(x)
0.48 °C/100g
Weight per Degree f(x)
325 g/°C
Bag Type
Mummy sleeping bag
Where to buy
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Category context Sleeping Bags (417 products)
Weight
Standard weight· mainstream zone 819–1420 g· ranked 270 of 418