Enter the leg to torso ratio and the leg length (in) into the Torso Length Calculator. The calculator will evaluate the Torso Length.
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Torso Length Formula
The calculator uses a different formula for each mode.
Estimate from height:
T = H * p
Measured torso:
T = L_measured
Measure a pack:
T_pack = L_anchor_to_belt + 2 in
- T = torso length (inches or cm)
- H = total standing height
- p = torso proportion factor (0.24 short, 0.27 average, 0.30 long)
- L_measured = direct tape measurement from the C7 vertebra to the top of the iliac crest
- L_anchor_to_belt = distance on the pack from the shoulder strap anchor point down the back panel to the center of the hip belt
- T_pack = effective torso length the pack will fit
Assumptions: the height-based estimate assumes a typical adult build. It is a starting point only. A direct measurement is more accurate, since two people with identical heights can have torso lengths that differ by 2 inches or more. The +2 inch offset on the pack measurement accounts for the strap material above the anchor point that wraps your shoulder.
Mode functions:
- Estimate from height applies the proportion factor to your height. Use this if you cannot measure yourself.
- Measured torso takes a direct C7 to iliac crest measurement and converts to inches if needed. Most accurate input.
- Measure a pack takes the back panel distance on a backpack and adds 2 inches to give the body torso length the pack is built for.
Reference Tables
Use the first table to match a torso length to a standard pack size. Use the second table to sanity check your height-based estimate.
| Pack Size | Torso (in) | Torso (cm) |
|---|---|---|
| Extra Small | under 15 | under 38 |
| Small | 15 – 17 | 38 – 43 |
| Medium / Regular | 17 – 19 | 43 – 48 |
| Large / Tall | 19 – 21 | 48 – 53 |
| Extra Large | over 21 | over 53 |
| Height | Short build (×0.24) | Average (×0.27) | Long build (×0.30) |
|---|---|---|---|
| 5'2" (62 in) | 14.9 in | 16.7 in | 18.6 in |
| 5'6" (66 in) | 15.8 in | 17.8 in | 19.8 in |
| 5'10" (70 in) | 16.8 in | 18.9 in | 21.0 in |
| 6'2" (74 in) | 17.8 in | 20.0 in | 22.2 in |
| 6'6" (78 in) | 18.7 in | 21.1 in | 23.4 in |
How to Measure and Common Questions
How to measure your torso:
- Tilt your head forward. Find the bony bump at the base of your neck. That is the C7 vertebra and it is the top of your torso measurement.
- Place your hands on top of your hip bones with thumbs pointing toward your spine. The imaginary line between your thumbs is the iliac crest line. That is the bottom of your torso measurement.
- Have someone run a soft tape measure along the curve of your spine from C7 down to that line. Stand up straight while they measure.
Example 1 — height estimate. You are 5'10" (70 in) with average proportions. T = 70 × 0.27 = 18.9 in. That puts you in a Medium / Regular pack.
Example 2 — direct measurement. You measure 17.5 in from C7 to your iliac crest line. That falls in the Medium / Regular range (17–19 in).
Example 3 — pack measurement. A used pack measures 16 in from the shoulder strap anchor to the hip belt center. T_pack = 16 + 2 = 18 in, so it fits a Medium torso.
Why does my height-based estimate differ from my measured torso? Body proportions vary. Two people who are 5'10" can have torso lengths anywhere from about 16.8 in to 21.0 in. Always trust a tape measurement over an estimate.
What if I am between two sizes? Most packs have an adjustable harness that covers a 2 to 4 inch range. If your torso lands at the boundary, pick the size where your measurement is in the middle of the adjustment range, not at the edge.
Does torso length change? Adult torso length is stable. It can shorten slightly with age due to disc compression, but day to day it does not change. Posture during measurement matters more than anything else.
Can I measure myself? It is hard to get an accurate number alone. If you have to, mark C7 and the iliac crest line with tape against a wall, then measure between the marks. Getting help is faster and more accurate.
