Calculate supported hangboard load and body-mass percentage, or reverse the arithmetic for added weight or assistance at a target percentage.
What Hangboard Load Means Here
This calculator treats a hangboard setup as simple external-load arithmetic. Body mass is the starting load. Added mass raises the modeled supported load, while effective assistance at the climber lowers it. Counterweight mass equals the assistance mass equivalent only for an ideal1:1 pulley; geometry and friction can change the transmitted assistance. The calculation does not decide which hold, grip, arm position, hang time, rest period, set count, or weekly frequency is appropriate. Those choices change the training stimulus and should not be inferred from one percentage.
For an added-load hang, supported mass = body mass + added mass. For an assisted hang, supported mass = body mass – assistance mass. Relative load is 100 x supported mass / body mass. In inverse modes, the calculator rearranges those equations to find added mass or assistance from a target percentage supplied by the user.
| Body mass | Adjustment | Supported mass | Relative load |
|---|---|---|---|
| 70 kg | Add 14 kg | 84 kg | 120% |
| 70 kg | No adjustment | 70 kg | 100% |
| 70 kg | Assist 14 kg | 56 kg | 80% |
Using the Inverse Modes
If a climber has already selected a target load through an appropriate training plan, added-load mode calculates the external mass above body mass. A 70-kilogram climber entering 130 percent gets 21 kilograms of added mass and 91 kilograms of supported mass. Assistance mode performs the mirror calculation below body mass. A 75 percent target for a 165-pound climber produces 41.25 pounds of assistance.
Keep Measurements Comparable
A result is only comparable with another session when the setup is consistent. Record the same edge depth and profile, grip, number of hands, elbow and shoulder position, hang duration, assistance geometry, scale, and warm-up state. Pulley friction and inaccurate plates or counterweights can make the actual support different from the entered value. Single-arm and two-arm hangs may show the same external system mass while placing that mass through different numbers of hands.
Training and Injury Limitations
Fingerboard loading can stress fingers, elbows, and shoulders. Progress gradually, use qualified coaching when the technique is unfamiliar, and stop when pain or a suspected injury is present. Young climbers and anyone returning from injury need especially careful, individualized guidance. A body-mass percentage is a bookkeeping result, not a safe-load threshold, performance grade, or instruction to train at that intensity.
Sources
British Mountaineering Council: How to Fingerboard
Stien and colleagues: Hangboard Training in Advanced Climbers, 2021
National Institute of Standards and Technology: NIST Guide to the SI, Appendix B, 2025 edition.
