Two lifters walk into a competition. One weighs 59 kg, the other 120 kg. Both total the same Wilks score. But according to the International Powerlifting Federation's own data, one of them has been systematically advantaged for decades — and it probably isn't who you'd expect.
When Robert Wilks published his bodyweight normalisation formula in the 1990s, it was a genuine leap forward for powerlifting. For the first time, a 75 kg lifter and a 110 kg lifter could be meaningfully compared. Coaches could debate who had relative strength across weight classes. Federations could crown overall champions without simply rewarding whoever weighed the most.
But the Wilks formula contained a structural flaw that only became fully apparent as the sport's dataset grew.
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The Wilks equation is a fifth-degree polynomial fitted to competition data from a specific era of the sport. Like all polynomial regression models, it fits well in the middle of the data range and wobbles at the extremes. For lifters below 60 kg and above 110 kg, the Wilks formula systematically over- or under-rewards performance depending on bodyweight.
A 2018 analysis of IPF world records found that very heavy lifters (>100 kg) were artificially inflated in Wilks terms relative to what the underlying biomechanics and physiology would predict. Shorter moment arms, larger cross-sectional area, and proportionally greater bone mass all contribute to genuine absolute strength advantages at heavier bodyweights — but the Wilks polynomial was overcorrecting for these differences at the extremes.
Simultaneously, the lightest weight classes were being slightly penalised. The result: overall championships at IPF events were won disproportionately by heavier lifters, even after Wilks normalisation.
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In 2019, the IPF officially retired the Wilks score and adopted the IPF GL coefficient (also called IPF Points). The new formula was developed by Jürgen Eckert and published in the *Open Powerlifting* dataset, fitted to a far larger and more contemporary pool of world-class competition results.
The GL coefficient uses a different mathematical form — a ratio of two fourth-degree polynomials — which behaves more stably at bodyweight extremes. The practical difference:
- A 59 kg female lifter who totals proportionally the same as an 84 kg female now scores identically on IPF GL, whereas Wilks would have slightly penalised the lighter lifter.
- At superheavyweight (>120 kg in men), the GL formula awards fewer points per kilogram of total than Wilks did, closing the historical advantage.
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For athletes, coaches, and sport scientists, the practical implications are significant.
First, historical Wilks comparisons are unreliable at bodyweight extremes. If you are tracking a superheavy athlete's progression using Wilks scores from five years ago, you may be comparing apples with oranges relative to today's IPF GL-tracked peers.
Second, the formula you use matters for goal-setting. A lifter targeting an elite IPF GL score should use that formula to benchmark their total — not Wilks. The targets differ meaningfully at lighter and heavier classes.
Third, for masters athletes and youth athletes competing across age-and-weight classifications, the GL formula provides cleaner comparisons across time and cohort. Masters records are increasingly being tracked in GL points rather than Wilks, reflecting the shift.
The underlying principle — normalise total lifted mass by bodyweight to enable cross-class comparison — is sound sports science. The debate is purely about which mathematical function fits the data best. By every modern analytical standard, IPF GL and Dots outperform Wilks. The sport's governing body has spoken.
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For anyone serious about tracking relative strength progression across bodyweight classes, moving beyond a single number toward understanding what the formula is actually measuring is the first step. Whether you are a powerlifter chasing a total, a strength coach comparing athletes, or a researcher studying force production, knowing which formula you are using — and its limitations — matters as much as the number itself.
Calculate your IPF GL score and compare it against historical Wilks benchmarks to see how the shift in formula affects your relative position at winsport.uk/tools/strength/wilks-score-calculator — it also shows how your total would rank under both coefficient systems simultaneously.
Which formula does your federation currently use — and do you think the switch to GL was the right call?