One Rep Max (1RM) Calculator – Epley

Your one rep max is the heaviest weight you can lift once with good form. Testing it directly is risky, so this calculator estimates it from a hard set of 1–12 reps using three published formulas: Epley (the 1985 classic), Brzycki (more conservative above 10 reps) and Lander, then averages them. Accuracy peaks at 3–6 reps, where formulas agree within about 5%. Worked example: lifting 100 kg for 5 reps gives Epley 100 × (1 + 5/30) = 116.7 kg, Brzycki 100 × 36/32 = 112.5 kg and Lander 10000 ÷ 87.9 = 113.7 kg — an average estimate of roughly 114 kg, with a working set of 85.5 kg at 75%.

1. 1

   Enter your set

   Type the weight you lifted and the clean reps you completed

2. 2

   See three estimates

   Epley, Brzycki and Lander results appear with their average

3. 3

   Use the table

   Training loads from 65% to 95% of your estimated max

• 1

  Use a 3–6 rep set for the most accurate estimate

• 2

  Re-estimate after every 5 kg change in working weights

• 3

  Warm up to the test set with at least 3 ramping sets

• Estimating from a 12-rep grinder set, where error exceeds 10%

• Grinding reps with breakdown in form, inflating the estimate

• Treating the average as exact — treat it as a range of ±5%

• Adding 10% "for adrenaline" when selecting training weights