Sleeping Bags
Camping & Climbing · 8 specs
Direct Answer
Sleeping bag temperature ratings are standardized internationally under ISO 23537-1 (which superseded European standard EN 13537). Using a calibrated thermal manikin in a climate chamber, tests establish four standardized temperature metrics: Comfort Temperature (T_comf, where a standard woman sleeps comfortably in a relaxed posture), Limit Temperature (T_lim, where a standard man sleeps in a curled posture without shivering), Extreme Temperature (T_ext, minimum survival threshold for women against hypothermia for 6 hours), and Maximum Temperature (T_max).
Source: ISO 23537-1 (Requirements for sleeping bags–Thermal and dimensional requirements) / EN 13537 · Last reviewed Aug 28, 2026
Specs
| Testing Standard | ISO 23537-1 (Supersedes EN 13537) Thermal Manikin Standard |
| Comfort Temperature (T_comf) | Standard Adult Female (25 yrs, 60 kg, 1.60 m) Relaxed posture without feeling cold |
| Limit Temperature (T_lim) | Standard Adult Male (25 yrs, 70 kg, 1.73 m) Curled posture without shivering for 8 hrs |
| Extreme Temperature (T_ext) | Hypothermia Survival Threshold for Female 6-hour survival limit without frostbite/death |
| Down Fill Power (FP) Tiers | 600, 700, 800, 850, 900+ cu in/oz IDFB Loft Volume Standard |
| RDS Down Certification | Responsible Down Standard (RDS) or Downpass Ethical Sourcing |
| Synthetic Insulation Types | Continuous Filament (Climashield) or Short-Staple (PrimaLoft) Moisture-resistant polyfill |
| Standard Internal Length | Regular: 180–185 cm / Long: 195–200 cm Internal Usable Length |
ISO 23537-1 Thermal Manikin Testing Protocol
- The Thermal Manikin: The bag is placed on a standard sleeping pad (R-value ~4.0) over an elevated wooden bed in a climate chamber. A heated copper manikin fitted with 20 thermal zone sensors measures heat loss (in watts/m²·K) across its surface wearing standard base-layer underwear (thermal shirt, long underpants, socks).
- Consumer Buying Rule: Female and cold sleepers should strictly choose bags based on the Comfort rating; experienced warm male sleepers can use the Limit rating. The Extreme rating is an emergency survival threshold, not a usable camping temperature.