Northern Warmth Gear
Sizing & Fill Guide
Fill weight is one of the most practical metrics for understanding the thermal performance and bulk of a sleeping bag. This guide explains how to choose the right fill weight and how to optimize your complete sleep system for the trail.
Choosing the Right Fill Weight
Fill weight refers to the total mass of insulation packed inside the bag, measured in grams. Use the table below to select the appropriate option for your intended trips and season.
| Fill Weight | Target Usage & Conditions |
|---|---|
| 300 g | Warm summer nights, hostels, bothies, and campervans when temperatures stay mild. Ultra-lightweight and compact. |
| 400 g | Mild summer camping, hut-to-hut touring, and warm-weather trips requiring low pack volume. |
| 600 g | Late spring to early autumn 3-season camping in the UK, and general mild-weather outdoor use. |
| 800 g | Cool 3-season nights and shoulder-season trips when ground temperatures drop overnight. |
| 1000 g | Cold autumn and early winter nights, and exposed campsites where conditions turn chilly after dark. |
| 1200 g | Winter camping under canvas where reliable insulation is essential for a good night's sleep. |
| 1500 g | Cold winter wild camping, frozen ground conditions, and static basecamp setups. |
| 1800 g | Sub-zero camping and for users who naturally sleep colder than average. |
| 2000 g | Cold-weather expeditions and high-altitude use requiring maximum insulation density. |
If you are deciding between two options, we recommend choosing the heavier fill weight. A warmer bag can easily be unzipped for ventilation, whereas an under-insulated bag cannot be adjusted at 3 a.m.
Shell Fabric & Downproof Construction
The shell fabric serves two vital functions: retaining the insulation evenly and shedding moisture or condensation that forms inside a tent. Our bags utilize high-density, downproof weaves designed to prevent insulation leakage while maintaining breathability.
The Complete Sleep System
Insulation compressed directly underneath your body loses much of its loft during sleep. As a result, the underside of any sleeping bag provides minimal insulation against conductive heat loss into the ground.
A quality sleeping mat is an essential component of your setup. Up to 50% of your total insulation comes from the barrier beneath you. If you are preparing for cold ground conditions, pairing your sleeping bag with an insulated mat is critical for maintaining warmth.
Care Instructions
- Storage: Always store your sleeping bag uncompressed in a loose storage sack or hanging. Prolonged tight compression degrades the insulation's loft over time. Use the compressed stuff sack only while traveling.
- Washing: Wash only when necessary using a technical, down-specific detergent on a gentle cold cycle.
- Drying: Tumble dry on low heat with two clean tennis balls or dryer balls to restore loft and break up clumps. Multiple low-heat cycles may be required. Do not dry clean.