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Fit and sizing

Torso length

Also called back length

What is torso length?

Torso length is the distance from the bony bump at the base of your neck down to the top of your hip bones. It's the measurement backpack sizes are built around, and it has almost nothing to do with how tall you are.

Torso length at a glance

Typical adult range
15 to 21 in
Measured from
C7 vertebra to iliac crest
Common size split
S under 17 in, M 17 to 19 in, L over 19 in
varies by brand

How to measure your torso

Find the knobbly vertebra at the base of your neck, the one that sticks out when you tip your chin to your chest. That's C7. Now put your hands on your hips with your thumbs pointing backwards until they meet in the middle of your lower back. That line is the top of your pelvis. The distance between those two points is your torso length, and it's usually somewhere between 15 and 21 inches.

Why your height tells you nothing

Two people the same height can be two full pack sizes apart, because height is mostly legs. That's why every serious pack maker publishes a torso range for each size instead of a height range, and why buying a large because you're six foot is how people end up with a pack that rides badly and gets blamed for being a bad pack.

Getting an accurate number

Get someone else to measure you if you can. Measuring your own back with a tape while keeping it straight is awkward enough that most self-measurements come out short. Stand normally, don't slouch, and let your arms hang.

What this means when you're choosing

  • The torso range printed for each size, not the height range
  • Whether the pack has an adjustable backpanel, which buys you two or three inches of tolerance
  • Where you land in the range: near the top of a size usually fits better than near the bottom

Work it out

Torso length to frame size

Pack sizing runs off your torso, not your height. Measure from the C7 vertebra at the base of your neck down to the level of your iliac crest.

Frame size, most brands

Medium / Regular

Ranges differ by maker and several run their own scale, so treat this as where to start rather than what to order. Hipbelt size is measured separately, at the iliac crest.

The common mistake

Shopping by height

Height tells a pack maker nothing useful. A 5'8" hiker with a long back and a 6'1" hiker with long legs can need the same size, and the height charts some retailers publish will send both of them wrong.

Common questions

How do I measure my torso length alone?

Hold one end of a soft tape at the base of your neck with one hand and run it down your spine with the other, then mark where your thumbs meet at your hips. It works, but it reads short more often than not, so treat a solo measurement as a floor rather than a number.

What if I'm between two pack sizes?

Take the larger one if the pack has an adjustable backpanel, since you can shorten it. If it's a fixed-length frame, the smaller size usually rides better, because a frame that's too long pushes the load lifters above your shoulders where they stop doing anything.

Where this is defined

Where this comes up

Guides on Tom's Hiking where torso length changes which product is right for you.

More in fit and sizing

Iliac crest

The iliac crest is the curved top edge of your pelvis, the ridge you feel when you put your hands on your hips. It's the shelf a backpack hipbelt sits on, and the lower anchor point for measuring torso length.

Last

A last is the foot-shaped mould a shoe or boot is built around. It sets the width, the volume, the shape of the toe box and the heel cup, which is why two pairs in the same size from different brands can fit completely differently.

Toe box

The toe box is the front of a shoe, from roughly the ball of the foot forward. Its width and height decide whether your toes can splay under load, which is what stops black toenails and blisters on long descents.

Surgeon's knot

A surgeon's knot is a lacing trick where you wrap the laces twice instead of once before pulling tight. The extra wrap holds tension in place, letting you lock your heel down while leaving the toe box loose.

Gusseted crotch

A gusseted crotch is an extra diamond or triangle of fabric sewn into hiking pants so four seams do not meet at a single point. It spreads the load of a high step across several seams, which is why gusseted pants do not bind or split at the crotch.

Short liner

A short liner is the brief, boxer or compression layer sewn inside running shorts and worn instead of underwear. Its cut is what decides whether long runs chafe: a brief covers little, a boxer liner reaches the inner thigh, and a 2-in-1 anchors to the shell so it cannot ride up.

Inseam

Inseam is the length of a garment's inner leg seam, measured from the crotch to the hem, and it is how running shorts are sized. Trail shorts run from about three inches to nine, and five to seven covers most trail running.

Chafing

Chafing is skin worn raw by repeated friction, usually where wet fabric rubs skin or skin rubs skin over hours. On a run it starts at the inner thigh, and dried sweat leaves abrasive salt behind that makes it considerably worse.

Last reviewed . Back to the glossary