Sleeping Bag Temperature Rating Converter
Interpreting Temperature Ratings
Sleeping bags are often rated with both “comfort” and “limit” temperatures. The comfort rating generally describes the lowest temperature at which an average sleeper will remain comfortable without feeling cold. The limit rating indicates the threshold for staying alive in harsh conditions. Manufacturers use lab tests based on standardized protocols, but personal factors—such as metabolism, shelter type, and clothing—affect real-world performance. It helps to convert between Fahrenheit and Celsius so you can compare gear from different brands.
Modern bags sold in Europe and many other parts of the world now follow the EN/ISO 23537 standard. These laboratory tests place a sensor-equipped mannequin inside the bag while the surrounding environment is held at specified humidity and wind levels. The resulting data yield “comfort,” “limit,” and sometimes “extreme” ratings. Extreme is a survival-only number—hypothermia may still occur. When comparing bags, check whether the listed ratings are EN/ISO certified or simply the manufacturer’s estimate.
Because each individual sleeps differently, consider the published numbers a baseline. Cold sleepers may want a bag rated 5–10 degrees warmer than the lowest temperature expected. Hot sleepers might choose a lighter bag and vent it on milder nights. Many hikers keep a sleep diary, noting nighttime lows and comfort levels, to dial in the best combination of bag, pad, and clothing.
The Conversion Formula
To convert Fahrenheit to Celsius, subtract 32 and multiply by 5/9. To convert Celsius to Fahrenheit, multiply by 9/5 and add 32. In MathML, that's and . This calculator performs the conversion automatically and shows the equivalent value on the other scale.
Temperature conversion also lets you interpret weather forecasts and backcountry trip reports written in a different system. If a guidebook says alpine nights drop to −7 °C, quick math reveals you should pack for about 19 °F. Familiarity with both scales helps when renting gear abroad, planning international trips, or shopping from global retailers that may list only one unit.
Sample Ratings Table
The following table demonstrates typical ranges for three-season sleeping bags. These values are just examples—always check the manufacturer's specific rating.
| Comfort (°C) | Comfort (°F) | Limit (°C) | Limit (°F) |
|---|---|---|---|
| 5 | 41 | -1 | 30 |
| 0 | 32 | -7 | 19 |
| -5 | 23 | -12 | 10 |
While tables like this offer a starting point, the bag’s cut, insulation type, and your body shape influence how warm it feels. A roomier mummy bag may be more comfortable for broad-shouldered campers but leaves more dead air space to heat. Slim alpine bags shave weight but can feel confining. Down insulation offers excellent warmth-to-weight ratios but must be kept dry. Synthetics insulate better when damp and cost less, though they pack bulkier.
Choosing the Right Bag
When selecting a sleeping bag, consider the lowest nighttime temperature you expect on your trips. Layering clothing inside the bag can extend its range by a few degrees. A well-insulated sleeping pad also prevents heat loss to the ground. Keep your bag clean and dry for maximum performance. Over time, down and synthetic fills compress, reducing warmth—track the comfort rating so you know when it's time to replace or professionally clean the bag.
The equation can help account for layering, where is the bag rating and is the warmth added by clothing in degrees. Adjust this factor based on personal experience and the type of layers you plan to wear.
Accessories can further widen a bag’s comfort range. Lightweight silk or synthetic liners add a few degrees of warmth while keeping the interior clean. Some backpackers drape an insulated jacket over the footbox to prevent cold toes. Double‑wide rectangular bags suit car-camping couples, whereas modular systems let you zip two bags together for shared warmth on long expeditions.
Storage habits also affect longevity. Compressing a down bag for months flattens the loft, so store it loosely in a breathable sack. Dry the bag thoroughly after trips—mildew not only smells bad but also breaks down the insulation fibers. Spot clean with a gentle soap, or follow the manufacturer’s washing instructions for a full refresh.
How This Converter Helps
Use this converter whenever you shop for new camping gear or compare global brands. Copy the result for quick reference while you plan your adventures. If you keep a spreadsheet of gear specifications, the copy button saves time by grabbing the formatted output for pasting into your notes.
The tool also suggests a season rating based on the converted value. Knowing whether a bag is best for summer, three-season, or winter use simplifies gear selection, especially for newcomers who may not yet understand how raw temperature numbers translate to field comfort.
Final Reminders
Sleeping well is essential for recovery and morale in the backcountry. Test your setup on a local overnight before committing to a long trip, and remember that weather forecasts can change. Carrying a slightly warmer bag than you think you need is insurance against unexpected cold snaps.