Sinclair Coefficient Calculator

Weightlifting’s bodyweight adjustment from the formula the IWF publishes: ten to the power of A × (log₁₀(bodyweight ÷ b))², and exactly one at or above b. A and b are refitted every Olympic cycle, so the cycle is an input and there is a field for a sheet this page has not read.

The published closed form

The two coefficient sets this page could source

What the cycle change does to the same lifter

A formula refitted every four years, and what that costs

This page is about the strength sports — powerlifting, the squat, bench press and deadlift, and weightlifting, the snatch and the clean and jerk. They are different sports under different bodies, the International Powerlifting Federation and the International Weightlifting Federation, and almost nothing carries from one rulebook to the other. Every figure below that belongs to an edition, a rulebook date or an Olympic cycle is printed with it, because both bodies revise them.

Why a score like this exists. A total in kilograms ranks lifters inside one weight class and nowhere else, and the heavier lifter lifts more almost without exception. A bodyweight-adjusted score multiplies the total by a coefficient that falls as bodyweight rises, so a federation can award one best-lifter prize across the classes. It is a comparison against one published curve and nothing more — not a measure of talent, not a prediction, and not transferable between the two sports, which use different formulas fitted to different data.

Weightlifting’s answer is not powerlifting’s. Where Wilks, DOTS and the IPF’s GL points all divide a constant by a function of bodyweight, the Sinclair coefficient raises ten to a power: A times the square of the base-ten logarithm of bodyweight divided by a reference bodyweight b. At or above b the coefficient is defined to be exactly 1, so a superheavyweight’s Sinclair total is simply their total and everyone lighter is scaled up toward it — which is also why a Sinclair coefficient cannot be compared with a Wilks one at all.

The edition is half the answer. A and b are refitted for each Olympiad — a provincial federation republishing the IWF’s figures states they are “derived statistically and calculated for one Olympic cycle” of four years beginning the year after the Games — and the two sets this page could source show what that costs: a 70 kg man with a 400 kg total scores 527.096 on the 2017-2020 coefficients and 553.543 on the 2021-2024 ones, over twenty-six kilograms apart. Almost all of that is b, which moved from 175.508 to 193.609 kg for men because b is the record holder’s bodyweight in the heaviest category and the record changed hands. The women’s b moved by 102 grams and their scores by under half a kilogram. So a Sinclair total without its cycle is not a comparable number.

The number this page cannot look up for you, it asks you for. This calculator has no table interpolation of any kind, and a curve fitted to stand in for a published table is worst at its extremes — exactly where the answer changes anything. So where a coefficient belongs to a cycle this page does not have, there is a field for it: enter the figure from the sheet your federation is scoring on and the arithmetic runs against your number rather than a stale one.

What could not be sourced, stated plainly. No 2025-2028 coefficient set was found. The IWF’s own download centre lists no document whose title mentions Sinclair or coefficients, and its Technical and Competition Rules & Regulations 2025, read as far as the fetch reached, contains no Sinclair formula anywhere. The provincial federation page that republishes them still prints “The above formulae are for the 2021-2024 cycle”. A current set may well exist; it was not reachable, and this page will not invent one. That is what the third cycle option is for.

Thirty-odd coefficients in a PDF is exactly the shape a confabulated table takes, so none was trusted on its own. Every set here was read from a federation document, corroborated against a second independent source, and then checked by reproducing figures the federations themselves published — a scoresheet column recomputed from the formula, not a table cell quoted back. That is the only check that catches an internally consistent wrong coefficient, and on this batch it caught one.

The reproduction is unusually clean. The IWF-hosted document works one example — a woman at 67.80 kg with a 257 kg total — and prints four intermediate figures: X = −0.355605203, A·X² = 0.099520681, a coefficient of 1.257536738 and a Sinclair Total of 323.187. All four come out of the formula on this page to every decimal printed. That is worth saying because the rest of the document did not come through: its formula block is garbled, its two appended graphs are images, and the bodyweight-to-coefficient tables it says it contains are absent from the extracted text, so nothing is quoted from them. It also disagrees with itself, with headers reading “C.W.F.H.C. AND I.W.F.” against a cover saying “WCH AND IWF”. The coefficients were corroborated from a second federation before being used.

What it does not do. It does not adjust for age — the masters coefficients are a separate published table by age, and this calculator has no table interpolation of any kind — and it says nothing about weight classes, which the IWF revised with effect from 1 August 2026. The weight class and bodyweight interpreter carries both IWF sets, and for powerlifting’s four competing formulas see Wilks and DOTS and IPF GL points.

This is the third place in this section where a governing body’s “scoring table” turns out to be a published closed form rather than a lookup, after the combined events scoring calculator — the decathlon and heptathlon tables — and the World Aquatics points calculator, a cubic. Where a table really is a table this section says so and takes the reader’s own figure, as the age-graded performance calculator does with its age factor.

Frequently asked questions

Related calculators

References

1. Alberta Weightlifting Association. The Sinclair Coefficients for the Olympiad January 1, 2021 to December 31, 2024, hosted on the IWF’s own download centre at iwf.sport (read 15 Oct 2026; about 5,000 to 6,000 characters). A provincial federation’s document on the international federation’s server, which is as close to an IWF publication of the coefficients as this batch could get. Gives A = 0.722762521 and b = 193.609 for men and A = 0.787004341 and b = 153.757 for women, printed twice to different precisions (0.722 762 520 996 and 0.787 004 341 02 on page 3). Its worked example reproduces exactly: a woman at 67.80 kg with a 257 kg total gives X = −0.355605203, A·X² = 0.099520681, a coefficient of 1.257536738 and a Sinclair Total of 323.187, and all four come out of the formula to every decimal printed. What did not come through: the formula block is garbled, so are the least-squares sums and the dimensional-analysis exponents; the two appended graphs are images; and the bodyweight-to-coefficient tables the document says it contains are absent from the extracted text, so nothing is quoted from them. The document also contradicts itself in places, with headers reading “C.W.F.H.C. AND I.W.F.” against a cover saying “WCH AND IWF”, and pages 3 to 6 headed “(2017-2020)”.
2. British Columbia Weightlifting Association. “Sinclair Formula”, bcweightlifting.ca (read 15 Oct 2026). An independent corroboration from a second federation in a different notation: it prints the arithmetic as spreadsheet formulas, “=Total*(10^(0.722762521*((LOG10(Bodyweight/193.609))^2)))” for men and the same shape with 0.787004341 and 153.757 for women, labelling 193.609 and 153.757 the “Maximum BWT”. States that “The above formulae are for the 2021-2024 cycle”, that the coefficients are “derived statistically and calculated for one Olympic cycle” of four years beginning the year after the Games, that the IWF publishes them and that it also uses Robi points. It gives no set for 2025-2028 either, and its 2017-2020 figures are in linked PDF charts that were not read.
3. “Sinclair coefficient”, en.wikipedia.org (read 15 Oct 2026). Cited for the 2017-2020 cycle, which the IWF’s own download centre no longer carries: A = 0.751945030 and b = 175.508 for men, A = 0.783497476 and b = 153.655 for women, for “January 1, 2017 to December 31, 2020”, sourced to the same Alberta Weightlifting Association document series hosted by the IWF. Attributes the method to R G Sinclair, Canadian Journal of Applied Sport Sciences, 1985, and describes b as “the world record holder’s bodyweight (in the heaviest category)”. Its own coefficient formula is garbled and the exponent expression is missing, so the shape of the formula on these pages comes from the two federation documents.
4. International Weightlifting Federation. Download centre, iwf.sport/downloads/ (read 15 Oct 2026). Cited for an ABSENCE rather than a value. No document on it has a title mentioning Sinclair or coefficients; the only rules documents listed are the TCRR as of 5 November 2025 and its annex, and the only other scoring item is a pair of “Robi Points” files with no year in either title. The centre shows a preview of each category rather than every file, so a 2025-2028 Sinclair sheet may exist behind a category link — it was not reachable from the listing, and no 2025-2028 coefficient set was found anywhere.
5. International Weightlifting Federation. Technical and Competition Rules & Regulations 2025, the file “as of 05 November 2025”, iwf.sport (read 15 Oct 2026; roughly 90,000 characters before the fetch truncated inside the Regulation to 3.3.3 tolerance chart, so later sections were not read). An absence worth naming: no “in force as from” statement appears in its readable text beyond its own 2025 title and the 1 August 2026 dates in section 1.2. Source for: the bodyweight categories of section 1.2, which print both the set in force at publication and the set effective 1 August 2026; ranking rule 6.8.2, under which equal results are separated by who achieved them earlier in the calling order and bodyweight does not break a tie at all, with “the athlete(s) who competed earlier in time” ranked higher across groups and rule 8.11 giving a tied record to “the athlete who completed the lift first”; rule 8.9, that “World Record(s) can only be broken in the bodyweight category and the age group where the athlete is entered”; and rule 3.3.3, specifying the discs as 25 kg red, 20 kg blue, 15 kg yellow, 10 kg green, 5 kg white, 2.5 kg red, 2 kg blue, 1.5 kg yellow, 1 kg green and 0.5 kg white, the men’s bar at 20 kg, the women’s at 15 kg and two collars at 2.5 kg each. The Sinclair formula is nowhere in the text read.