Climbing Finger Strength Ratio Calculator
Calculate your finger strength-to-weight ratio from hangboard max hang weight.
Compare results to benchmarks for V3 through V10+ grades and training zones.
How Climbing Finger Strength Ratio Is Calculated
Finger strength is the single strongest predictor of climbing performance. The standard measure is the maximum weight you can hang from a 20mm edge for 7-10 seconds using a half-crimp grip, expressed as a ratio of your body weight.
The Strength Ratio Formula
Strength Ratio = (Body_Weight + Added_Weight) / Body_Weight
If you cannot hang body weight, the added weight is negative (you used a pulley to remove weight):
Strength Ratio = (Body_Weight - Assistance_Weight) / Body_Weight
Benchmark Table by Climbing Grade
These benchmarks are based on data collected from hundreds of climbers by researchers including Eva Lopez and Lattice Training:
| Grade (French/V) | Min Ratio (20mm) | Typical Ratio |
|---|---|---|
| 6a / V3 | 0.80 | 0.90 |
| 6c / V5 | 1.00 | 1.10 |
| 7a / V6 | 1.10 | 1.25 |
| 7b / V8 | 1.30 | 1.45 |
| 7c+ / V10 | 1.50 | 1.65 |
| 8a / V11 | 1.60 | 1.80 |
| 8b / V13 | 1.80 | 2.00 |
| 8c+ / V15 | 2.00 | 2.20+ |
Worked Example
A 70 kg climber who can hang from a 20mm edge with 15 kg added:
- Strength Ratio = (70 + 15) / 70 = 1.21
- This corresponds roughly to a 7a (V6) climber
- To progress to 7b (V8), they need a ratio of ~1.30
- Target added weight: 1.30 × 70 - 70 = 21 kg
Edge Depth Conversion
The benchmark table above is all measured on a 20mm edge, so a result from any other edge has to be converted before you compare it. Smaller edges give lower numbers:
- an 18mm result is roughly 5% lower than the same climber’s 20mm result
- a 15mm result is roughly 15% lower
- a 10mm result is roughly 30% lower
To go the other way, which is what the calculator does, you divide rather than subtract. A 15mm result is 85% of the 20mm figure, so the 20mm equivalent is your result ÷ 0.85, a multiplier of 1.176. It is a common slip to multiply by 1.15 instead, and on the 10mm edge that error is worth nearly a tenth of a grade band.
| Edge | Result is | Multiply by |
|---|---|---|
| 20mm | the reference | 1.000 |
| 18mm | 5% lower | 1.053 |
| 15mm | 15% lower | 1.176 |
| 10mm | 30% lower | 1.429 |
These are rough. Edge conversion varies a lot between climbers, and someone with short fingers loses far less going from 20mm to 15mm than someone with long ones.
Training Progression
A realistic improvement rate for finger strength is 5-10% per training cycle (6-8 weeks). Attempting faster gains significantly increases the risk of pulley injuries. Always warm up thoroughly before maximal hangs and never train finger strength on consecutive days.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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