Sinclair Coefficients

The Sinclair Coefficients are a means to compare different weight classes in olympic weightlifting.

The answer to the question "What would be the total of an athlete weighing x kg if he/she were an athlete in the heaviest class of the same level of ability?" is given by the formula: ACTUAL TOTAL × SINCLAIR COEFFICIENT = SINCLAIR TOTAL.

There are eight bodyweight categories for male athletes: 56 kg, 62 kg, 69 kg, 77 kg, 85 kg, 94 kg, 105 kg and +105 kg, and seven for female athletes: 48 kg, 53 kg, 58 kg, 63 kg, 69 kg, 75 kg and +75 kg.

There are also two types of lifts: snatch, and clean and jerk. However, at the championships, medals are presented in both lifts separately, and in total (the combined result of the best snatch and the best clean and jerk).

To compare and rank the results, especially between bodyweight categories, the International Weightlifting Federation uses the Sinclair Coefficients which are derived statistically and calculated for one Olympic cycle (for four years, starting in the Spring of each Olympic year).

The total for each bodyweight category is a projection of the Total for that weightlifter if he/she were a competitor in the heaviest bodyweight category with the same level of ability. It is done in four body weight categories for the males (56 kg, 69 kg, 77 kg, +105 kg). For the other four categories (62 kg, 85 kg, 94 kg, 105 kg) the Sinclair Total represents the World Standard because nobody as of March 2008 has lifted the predicted total. Those projections using the Sinclair Total are shown below.

The Sinclair Coefficient is 10 A ( log 10 ⁡ ( x / b ) ) 2 . If x<b where x is the weightlifter's bodyweight, b is the world record holder's bodyweight (in the heaviest category) and A is the coefficient for this Olympic cycle, or 1.0 if x≥b.

Then, the Sinclair Total is simply the obtained total multiplied by the Sinclair Coefficient.

For example, from 2013 to 2016, a calculation of the Sinclair Coefficient might look like this:

A=0.794358141 for males A=0.897260740 for females b=174.393 kg for males b=148.026 kg for females Assume that we are assessing a male weightlifter weighing 61.9 kg with a total of 320 kg. Then, x=61.9 kg, and we have X=log10(x/b)=log10(61.9/174.393)=-0.449838400 A(X^2)=0.794358141*(-0.449838400)^2=0.794358141*0.20235459=0.160742013 10^(A(X^2))=10^0.160742013=1.447911485 Sinclair Total = Actual Total x S.C. = 320 kg x 1.447911485 = 463.332

To understand the whole idea, here is the chart with all male bodyweight categories (in kg) and its world record Totals, Sinclair Coefficients, and Sinclair Total. By looking at the Sinclair Total we can determine the RANK. * denotes a World Standard rather than a world record.

The same is done for the seven female body weight categories.