By Dana Okoro, Editorial Reviewer · Published September 14, 2026, 6:03 PM ET · Updated September 29, 2026, 6:16 PM ET
Direct Answer
Torso length is the distance down the spine from the C7 vertebra at the base of the neck to the iliac-crest line at the top of the hip bones. It's the measurement backpack manufacturers use to size a pack's frame and shoulder-strap position, and it's unrelated to overall height.
In plain English
Torso length is simply the length of your back, measured along your spine from the base of your neck to the top of your hips. It is not the same as your height, and not the same as the length of your shirt.
Backpacks care about this number because a hiking pack has two main contact points: the shoulder straps up top and the padded belt around your hips. The distance between them is fixed by your back length. If the pack is built for a longer back, the hip belt ends up too low. If it is built for a shorter back, the belt rides up onto your belly.
It is a bit like a bike frame. Two people of the same height can need different frame sizes because one has longer legs and the other a longer body. Measuring your torso once gives you a number you can use with any brand's chart.
Torso length is the distance down the spine between two specific bony landmarks: the C7 vertebra at the base of the neck, and the iliac-crest line at the top of the hip bones. It is not the same as height, shirt length, or waist-to-shoulder measurements used in clothing.
Why backpacks use torso length instead of height
A hiking backpack's frame has to bridge the exact span between where the shoulder straps sit and where the hipbelt sits, and that span is set by torso length, not overall body height. Two hikers who are both 5'8" can have torso lengths that differ by two or three inches, because torso-to-leg ratio varies by individual. Sizing packs to height would fit neither hiker reliably.
How torso length is measured
A flexible tape measure is run from the C7 vertebra — found by tilting the head forward and feeling for the bony bump at the base of the neck — down the curve of the spine to the iliac-crest line, located by placing hands on the waist with thumbs pointing backward to the top ridge of the hip bones.
Typical adult range
Adult torso lengths vary widely, and brands publish their own size bands; Granite Gear's, for example, run from 15 to 24 inches across its Short, Regular and Long sizes. A measured torso length is compared directly against a specific pack's torso-length chart, not against a generic clothing size or shoe size.
The two landmarks, as brands define them
The C7 vertebra is the top landmark for nearly every maker. Gregory describes finding it by tilting the head forward and feeling for the prominent bump where neck meets shoulders,1 and Granite Gear calls it the bony bump at the base of the neck that marks the top of the torso.2 The lower landmark is the iliac crest, the top ridge of the pelvis; Deuter defines back length as C7 to the upper edge of the iliac crest.3
One brand defines it differently. Mystery Ranch measures from C7 down the spine to a point just behind the belly button,4 so its torso numbers are not interchangeable with other brands' charts.
Why height is a poor substitute
Hyperlite states plainly that height is not a reliable proxy for torso length and that it should be measured.5 The page's example of two 5-foot-8 hikers whose torsos differ by two or three inches illustrates the idea, but the specific figure is not from a verified source; the underlying point, that leg-to-torso proportions vary, is what matters.
Some makers do link typical heights to back lengths for rough guidance. Deuter says its SL (women's) fit targets back lengths of about 42 cm for body heights of roughly 160 to 175 cm.3 Deuter also says women's SL packs use a shorter back panel matched to the average female torso, but Gregory sizes packs identically regardless of gender,1 so a measured number beats assumptions based on either height or gender.
What the typical range really looks like
Some guides give a typical adult range of about 15 to 21 inches. That range is not verified as a population figure, and brand size runs extend beyond it. Granite Gear offers torso sizes from 15 up to 24 inches,2 and Hyperlite's Southwest comes in five torso sizes from under 15 inches to 21 inches and up.6 Deuter's back lengths step from about 42 cm (SL) to 46 cm (regular) and about 50 cm (EL).3
Because packs with adjustable harnesses still have fixed ranges, Deuter advises that even adjustable packs be chosen in the correct back length.3 The measurement is a starting point; Kelty notes that fit still has to be checked on the body.7
