Key Takeaways
- The Sinclair coefficient is a multiplier that turns a weightlifting total into a bodyweight-adjusted score. The formula is 10 raised to A × (log10(bodyweight ÷ b))², and it equals 1 above b[1]. The Sinclair total is your total times that coefficient.
- The constants change every four years, which is why sites disagree. This page defaults to the 2025 to 2028 set and keeps 2021 to 2024 as an option[1][2]. The same 75.4 kg woman with a 270 kg total scores 322.135 on one and 321.169 on the other.
- Sinclair is no longer the official IWF method. A 2023 study says the IWF officially recognised the 2017 formula until late 2018[6], and the IWF now names Robi Points as its official way to compare totals[4]. USA Weightlifting switched its best-lifter awards to Q-points on 1 January 2025[5].
- Sinclair was fitted to world-record totals, mostly from lifters in their twenties, early thirties or late teens[1]. The same study found the 2017 version favoured heavier male lifters[6]. I found no test of the 2025 to 2028 constants.
- The optional age factor is the 2019 IWF Masters table. The IMWA has since moved to Q-Masters points with updated age factors[11]. I could not source a "good Sinclair score" scale, so I don't give one.
What the Sinclair Coefficient Does
A heavier lifter can lift more, so raw totals favour big athletes. The Sinclair coefficient is meant to answer one question: what would a lifter of this bodyweight total if they were in the heaviest category at the same level of ability[1]?
You multiply your actual total by the coefficient to get the Sinclair total. A lighter lifter gets a bigger multiplier, and at or above a set bodyweight the multiplier is 1.
The method comes from Roy Sinclair's 1985 paper in the Canadian Journal of Applied Sport Sciences[3]. The paper says the coefficients are adjusted each Olympic cycle, and both editions here come from Alberta Weightlifting Association papers[1][2].
The Formula and Its Constants
For a bodyweight of x kg, the coefficient depends on two constants, A and b. Each edition and each sex has its own pair:
| Edition | Men A | Men b (kg) | Women A | Women b (kg) |
|---|---|---|---|---|
| 2025 to 2028[1] | 0.700767819 | 201.159 | 0.674107991 | 163.918 |
| 2021 to 2024[2] | 0.722762521 | 193.609 | 0.787004341 | 153.757 |
Constants as printed in the Alberta Weightlifting Association papers. Bodyweight is in kilograms.
How the coefficient is worked out
- Convert your bodyweight to kilograms and call it x.
- If x is above b, the coefficient is 1 and you stop here.
- Otherwise work out X = log10(x ÷ b), then A × X².
- The coefficient is 10 raised to that power. The Sinclair total is your total times the coefficient.
Worked example from the 2025 to 2028 paper
The paper's own example is a woman of 75.4 kg with a total of 270 kg[1]. The calculator reproduces every figure below in its tests.
X = log10(75.4 ÷ 163.918) = -0.337255301
A × X² = 0.674107991 × X² = 0.076673810
Coefficient = 10^0.076673810 = 1.193091660
I recomputed all 3,054 coefficients in the 2025 to 2028 men's and women's tables from these constants, and each matched the printed value to six decimals[1]. I did the same for 1,617 rows of the 2021 to 2024 men's table[2].
For the 2021 to 2024 women's table I checked only 36 rows spread across it, so the rest is unchecked.
Coefficients by Bodyweight
These values are worked out by the same function the calculator uses, so you can check a result by hand against any row.
| Bodyweight (kg) | Men 2025 to 2028 | Men 2021 to 2024 | Women 2025 to 2028 | Women 2021 to 2024 |
|---|---|---|---|---|
| 50 | 1.803573 | 1.777678 | 1.510938 | 1.539276 |
| 55 | 1.668250 | 1.644037 | 1.417831 | 1.435091 |
| 60 | 1.561115 | 1.538466 | 1.344079 | 1.353466 |
| 65 | 1.474635 | 1.453435 | 1.284645 | 1.288359 |
| 70 | 1.403716 | 1.383858 | 1.236091 | 1.235690 |
| 75 | 1.344796 | 1.326184 | 1.195991 | 1.192612 |
| 80 | 1.295314 | 1.277863 | 1.162587 | 1.157078 |
| 85 | 1.253383 | 1.237021 | 1.134578 | 1.127585 |
| 90 | 1.217586 | 1.202248 | 1.110975 | 1.103002 |
| 95 | 1.186836 | 1.172466 | 1.091021 | 1.082465 |
| 100 | 1.160289 | 1.146839 | 1.074119 | 1.065301 |
| 110 | 1.117268 | 1.105536 | 1.047683 | 1.039077 |
| 120 | 1.084612 | 1.074466 | 1.028885 | 1.021224 |
| 150 | 1.026556 | 1.020654 | 1.002308 | 1.000209 |
Sinclair coefficients at selected bodyweights. 1.000000 means the bodyweight is above b for that edition.
Why Different Sites Give Different Numbers
The usual reason is the edition. Each four-year set has its own A and b, so the same lift scores differently depending on which set a site uses[1][2].
For the example above, the 2021 to 2024 constants give a coefficient of 1.189514 and a Sinclair total of 321.169 kg, against 1.193092 and 322.135 kg for 2025 to 2028. Use the edition that was in force when the result was lifted.
This calculator uses the constants as the papers print them, to nine decimals.
A typo in the 2021 to 2024 example
The 2021 to 2024 paper's worked example (a woman with a 257 kg total) prints a bodyweight of 67.9 kg inside the logarithm, but every number it prints matches 67.8 kg[2]. The tests use 67.8 kg, which reproduces its coefficient of 1.257536738 and its Sinclair total of 323.187.
Is Sinclair the Official IWF Method?
No, not any more. Huebner and colleagues write that the 2017 Sinclair formula was officially recognised by the IWF until late 2018 and is still used in many regional competitions[6]. The IWF now describes Robi Points as "the official IWF calculation method" for comparing Junior and Senior totals across bodyweight categories[4].
Robi Points are calculated from the world records in each category, with a record scoring 1000 points[4]. I found no mention of Sinclair in the IWF's 2026 Technical and Competition Rules and Regulations[9].
USA Weightlifting announced that from 1 January 2025 it would use Q-points to decide Best Lifter at national events, replacing Sinclair, Sinclair-Meltzer-Faber and Sinclair-Huebner-Meltzer-Faber[5]. The IMWA, which runs masters championships, uses Q-Masters points from the same date[11][12].
What the research says about the bias
Huebner and colleagues compared several scaling models on elite results. They report that the 2017 Sinclair formula favoured heavier male lifters, that a 2022 model reduced this for men, and that Sinclair and Robi points varied more across medallists than Q-points did[6].
That study looked at older constants, so it does not measure the 2025 to 2028 set. I found no equivalent test of the current constants.
So use Sinclair when a meet or club asks for it, and don't expect the same ranking you would get from Robi or Q-points.
Adding an Age Factor for Masters Lifters
The age box applies the Meltzer-Faber factors for men and the Huebner-Meltzer-Faber factors for women from the 2019 IWF Masters table[7]. The adjusted score is your Sinclair total times the factor. Both tables read 1.000 at age 30.
| Age | Men (MF) | Women (HMF) |
|---|---|---|
| 30 | 1.000 | 1.000 |
| 40 | 1.135 | 1.138 |
| 50 | 1.279 | 1.340 |
| 60 | 1.514 | 1.705 |
| 70 | 1.867 | 2.077 |
| 80 | 2.504 | 2.714 |
Age factors at selected ages. Men are covered from 30 to 90 and women from 30 to 80.
For example, a 50-year-old man at 89 kg with a 250 kg total has a Sinclair total of 306.078 kg on the 2025 to 2028 constants. Times the age factor of 1.279, that is 391.473 kg.
Why the age-adjusted score is not an official masters score
- The IMWA rulebook pairs these age factors with the 2020 Sinclair coefficients[8]. I don't have that set, so this page applies the factor to the edition you pick.
- Since 1 January 2025 the IMWA uses Q-Masters, which multiplies Q-points by age factors it updated with results up to the 2024 World Masters Championships[11][12]. I could not open that table, so it is not here.
- The men's table matched a second copy. The women's table rests on one copy[7], and I could not check it against another.
- The factors start at 30 and stop at 90 for men and 80 for women. Outside that range the calculator shows no adjusted score.
For background, the IMWA says the men's factors were first derived by David Meltzer and updated in 2015 with Friedrich Faber. It says the women's factors came from performances between 2013 and 2018 and were adopted in 2019[11].
Limits to Keep in Mind
- It was fitted to elite lifters. The paper says the coefficients rest on world-record totals of lifters mostly in their twenties, early thirties or late teens, so bodyweight should not be too far below the lightest category[1].
- Light lifters get a guideline, not a fit. The paper extends the curve to 32 kg for men and 28 kg for women "as a guideline for very young athletes"[1]. Below those weights the calculator warns you.
- It describes the records of one period. The paper bases the constants on world records of the previous several years, and its notes describe the ten categories per sex that the IWF introduced in 2018[1]. The IWF has used a new set of eight categories per sex since 1 August 2026[10], and I found no newly published Sinclair constants for them.
- Above b the coefficient is 1. That means men above 201.159 kg and women above 163.918 kg get no adjustment under the current set.
Using the Result
- Pick the edition that matches the result you are scoring. Use 2025 to 2028 for anything lifted in 2025 or later.
- To plan a target, switch to "Find the total I need". It divides your target Sinclair total by the coefficient.
- Treat age-adjusted scores as a rough comparison only, for the reasons above.
- For powerlifting, Wilks, DOTS and IPF GL points are a different family of scores, and the DOTS Calculator covers them. Sinclair is for the snatch and clean and jerk.
What This Page Doesn't Cover
I left these out because I couldn't trace them to a source I could open:
- A "good Sinclair score" scale. I found no official or peer-reviewed scale. A page that shows beginner, intermediate and elite bands has no source I could check.
- Robi Points and Q-points. I did not build either one. The IWF has its own Robi calculator[4], and the IMWA links to a Q-points calculator[11].
- The 2020 coefficients and the 2025 IMWA age factors. These would make an official masters score possible, but I could not get either table.
Still unverified: whether a revision newer than Rev 1.0 (March 2025) of the 2025 to 2028 paper exists, and whether the IWF has published its own refit for the categories in force from 1 August 2026.
Frequently Asked Questions
Sources & References
- The Sinclair Coefficients for the Olympiad, January 1, 2025 to December 31, 2028 (Rev 1.0). Alberta Weightlifting Association (document author field: Marc Poretti, based on work by Roy Sinclair). Alberta Weightlifting Association, March 2025 (2025)
- Sinclair Coefficients (2021-2024). Alberta Weightlifting Association. Hosted by the International Weightlifting Federation (2021)
- Normalizing the performances of athletes in Olympic weightlifting. Sinclair RG. Canadian Journal of Applied Sport Sciences 10(2):94-98 (1985)
- Robi Points. International Weightlifting Federation. iwf.sport (2026)
- Q-Points, Q-Youth to be Used in 2025 to Determine Best Lifters. USA Weightlifting. USA Weightlifting news, 19 November 2024 (2024)
- Comparison of Olympic-Style Weightlifting Performances of Elite Athletes: Scaling Models Account for Body Mass. Huebner M, Meltzer DE, Bjarnason A, Perperoglou A. Medicine and Science in Sports and Exercise 55(12):2281-2289 (2023)
- IWF Master age factors 2019 (MF for men, HMF for women). Men's table cross-checked against a second copy. German Masters Weightlifting (copy of the IWF Masters table); second copy: rudi-seidel.de. german-masters-weightlifting.de (2019)
- IMWA Handbook, 2023 edition (rules 5.2 and 5.3 on the SMF and SHMF formulas). International Masters Weightlifting Association. IMWA (2023)
- Technical and Competition Rules & Regulations 2026. International Weightlifting Federation. IWF (2026)
- Bodyweight categories for the 2028 Olympics in Los Angeles are defined. International Weightlifting Federation. IWF news, 3 November 2025 (2025)
- Calculator (Q-Masters points from 1 January 2025). International Masters Weightlifting Association. imwla.com (2025)
- IMWA Handbook, 2025/26 edition (rules 5.1 to 5.3 on Q-Masters points). International Masters Weightlifting Association. IMWA (2025)
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Disclaimer: This tool is for informational and personal journaling purposes only. Results are estimates based on published formulas and may vary based on individual factors such as genetics, training history, and measurement technique.