Sleeping Bag Temperature Ratings Explained

# Sleeping Bag Temperature Ratings Explained

Sleeping bag temperature ratings can be confusing. Here is what they actually mean, so you can choose the right bag for your Nepal trek.

## The ISO/EN Rating System

Bags are tested to ISO 23537 (formerly EN 13537) and given three ratings:

– **Comfort** — a cold sleeper stays warm. Use this for women and cold sleepers.
– **Limit (Lower Limit)** — a warm sleeper curled up stays warm. Use this for men and warm sleepers.
– **Extreme** — survival only. You will be very cold but survive. Never trek at this rating.

## Example

A bag rated Comfort -10°C / Limit -15°C / Extreme -40°C means:
– Most women sleep comfortably to -10°C
– Most men sleep curled up to -15°C
– Survival to -40°C (do not rely on this)

## Which Rating to Use?

For Nepal treks, use the **Comfort rating**. It gives you a safety margin.

– EBC, Annapurna Circuit, Manaslu: -10°C comfort
– Three Passes, Island Peak: -15°C comfort
– Expedition climbing: -25°C comfort

## Other Factors

– **Sleeping pad R-value** matters — a cold pad makes a warm bag feel cold
– **Your clothing** — wearing base layers adds warmth
– **Hydration** — being dehydrated makes you colder
– **Tent vs teahouse** — tents are warmer than unheated teahouse rooms

## Our Rental Fleet

– TrailPro -10°C (comfort) — most popular, for EBC/Annapurna/Manaslu
– TrailPro -15°C (down) — for Three Passes and cold sleepers
– SummitPro -25°C (expedition) — for climbing peaks