How to size sleeping bags
Measure the surface, then the overhang
Sleeping bag length should be 4–6″ longer than your height. Width is decided by shape: mummy (32–34″ at shoulder, tapered) for warmth and weight, rectangular (32–40″ at shoulder, straight cut) for comfort and at-home use, semi-rectangular as the middle ground.
Standard sizes vs. your actual surface
Manufactured "standard" sizes assume textbook measurements. Older homes, custom furniture, and non-standard windows often deviate by 1–3″. If the measurement falls between two stock sizes, choose the larger; it's easier to hem or tuck excess fabric than to add length you don't have.
Mounting and clearance
Compressed pack size matters as much as bag size for backpacking. A 3-season mummy compresses to about 7″ × 14″; a synthetic rectangular bag compresses to about 9″ × 18″. Match pack size to your backpack volume.
Common mistakes
- Measuring once. Surfaces are rarely perfectly square; take the smallest of three measurements.
- Forgetting shrinkage. Cotton items can lose 3–5% on the first wash.
- Ignoring drape. Heavier fabrics need an extra inch or two to hang correctly.