Hong Life CalculatorsUnderstanding the Sinclair calculator — concept and principle
The Sinclair coefficient lets Olympic weightlifters of different bodyweights be compared on one scale. It multiplies your total (best snatch plus best clean and jerk) by a factor that tells you what you would theoretically lift if you were as heavy as the heaviest world-class lifters. The International Weightlifting Federation (IWF) and national federations use it to pick the best lifter of a competition.
How it is calculated
If bodyweight is below b: coefficient = 10^(A × (log₁₀(BW ÷ b))²), otherwise coefficient = 1.
Sinclair total = total × coefficient.
- Total: snatch + clean and jerk, in kg.
- BW: bodyweight in kg.
- A and b: constants published for each Olympic cycle. The defaults are the 2021–2024 values: men A = 0.722762521, b = 193.609 kg; women A = 0.787004341, b = 153.757 kg. Enter new values in the two optional fields when the IWF publishes them.
The principle
When world-record totals are plotted against bodyweight on a logarithmic scale, they follow a curved line that rises and then flattens. Sinclair modelled this as a parabola in log₁₀(bodyweight). A is the curvature of that parabola and b is the bodyweight at its peak, which sits near the bodyweight of the heaviest record holders. The coefficient is simply the ratio between the predicted record at b and the predicted record at your bodyweight, so multiplying by it moves your total along the curve up to b. The curve is refitted to new records after each cycle, so A and b change.
Worked example
- Inputs: male, bodyweight 81 kg, total 300 kg, default constants A = 0.722762521, b = 193.609.
- log₁₀(81 ÷ 193.609) = log₁₀(0.41837) ≈ −0.37844.
- Square it: 0.143217; multiply by A: 0.103512.
- Coefficient = 10^0.103512 ≈ 1.27 (1.26915 before rounding).
- Sinclair total = 300 × 1.26915 ≈ 380.74.
| Bodyweight (kg) | Sinclair total |
|---|---|
| 20.2 | 1,485.84 |
| 40.5 | 646.85 |
| 60.8 | 457.36 |
| 81 | 380.74 |
| 101 | 342.3 |
| 122 | 321.16 |
| 162 | 303.01 |
How to read the result
The Sinclair total is in "kilograms as if you were a heavyweight", so a higher number means a stronger performance relative to bodyweight. It is most meaningful when comparing lifters of the same sex within the same cycle's constants. Lighter lifters always have larger coefficients; a 55 kg lifter gets a much bigger multiplier than an 89 kg lifter.
Common mistakes
- Using the coefficient for a single lift only; it is defined for the total, although many people apply it to one lift informally.
- Mixing constants from different cycles when comparing historical results.
- Entering bodyweight in pounds.
- Assuming the coefficient keeps rising above b; it is capped at 1.
Frequently asked questions
Why does my Sinclair total change when nothing else changed?
The IWF updates A and b after each Olympic cycle, so the same lift can give a slightly different score under new constants.
Where do I find the current coefficients?
The IWF publishes them on its official website and in its documents for each cycle. Type them into the two optional fields.
Sources: International Weightlifting Federation, Sinclair coefficients for the 2021–2024 Olympic cycle