Math
One-Rep Max (1RM) Epley & Brzycki strength formulas + 2.5 kg plate rounding
Estimate 1-Rep Max from submaximal sets using Epley W*(1 + Reps/30) and Brzycki W*36/(37 - Reps), plus nearest-2.5-kg training load rounding.
Compare two estimated lifting-load formulas with fictional inputs
Epley and Brzycki are prediction equations, not guarantees of a safe or achievable maximum. Estimates depend on exercise, technique, population, fatigue and how close the recorded set was to failure. This worksheet accepts whole repetitions from 1 to 10 as an explicit teaching range; it does not instruct users to perform a maximum or failure test.
At one repetition this worksheet returns the recorded load by convention. That does not prove the person could lift no more. The target fraction is a supplied arithmetic example, not a training recommendation. Rounding to the nearest 2.5 kg can round upward and does not verify the available plates, bar weight or an appropriate training load.
| Lift Input / Formula | Cell | 100 kg x 5 Reps Example | Result |
|---|---|---|---|
| Barbell Weight & Reps | B2 = 100 kg, B3 = 5 | 5-rep top set | One-repetition branch returns recorded 100 kg |
| Guarded Epley 1RM | IF(B3=1, B2, B2*(1+B3/30)) | 100 * (1 + 5/30) | 116.67 kg |
| Brzycki 1RM | B2 * 36 / (37 - B3) | 3,600 / 32 | 112.50 kg (more conservative) |
| 85% Working Load (2.5 kg step) | B4 = 0.85 | 112.50 * 0.85 = 95.625 kg | 95 kg rounded arithmetic result |
Guarded Epley 1RM formula
Use positive load and whole repetitions 1–10. The one-repetition branch returns the recorded load rather than claiming to measure the true maximum.
=IF(COUNT(B2:B4)<>3,"Invalid inputs",IF(OR(B2<=0,B3<1,B3>10,B3<>INT(B3),B4<=0,B4>1),"Invalid inputs",IF(B3 = 1, B2, ROUND(B2 * (1 + B3 / 30), 2))))Brzycki 1RM & nearest-2.5-kg barbell working load
The illustrative target fraction must be greater than zero and no greater than one. The 2.5 kg step refers to total barbell load, not a plate on each side.
=IF(COUNT(B2:B4)<>3,"Invalid inputs",IF(OR(B2<=0,B3<1,B3>10,B3<>INT(B3),B4<=0,B4>1),"Invalid inputs",ROUND(((B2 * 36 / (37 - B3)) * B4) / 2.5, 0) * 2.5))Try the example
Use the original values or change them to test your understanding.