🏋️ One Rep Max Calculator
Enter the weight you lifted and how many reps you completed to estimate your one-rep max (1RM) using the Epley formula, plus a percentage table for programming your training. For informational purposes only — always use proper form and spotters.
The Epley formula, then a percentage table
This page uses Epley, which adds a flat 1/30th of the load per rep completed. A single rep is returned untouched rather than run through the formula:
1RM = weight × (1 + reps / 30)
reps = 1 → 1RM = weight
training loads = 1RM × 95, 90, 85 ... 60%Five reps at 185 gives 215.8, and the table reads 194.3 at 90% and 172.7 at 80%. The tool is unitless: put in kilos and every row is kilos.
How far to trust it
- Fewer reps, better estimate. A triple predicts your max far more closely than a set of fifteen, which is why the input stops at 20.
- Epley runs high on long sets. Brzycki, the other common formula, returns 208.1 for that same 185 × 5, about 4% lower. The two agree exactly at 10 reps and diverge either side of it.
- The set has to be honest. The formula assumes you stopped because you could not do another rep; two left in reserve and the answer comes out low.
Frequently asked questions
What is my one rep max if I lift 185 for 5 reps?
About 216 by Epley: 185 multiplied by 1 plus 5/30. Brzycki puts the same set nearer 208, so read the mid-210s as an upper estimate.
What is the Epley formula?
1RM = weight x (1 + reps / 30). Each rep is worth roughly 3.3% of the weight lifted, so ten reps implies a max about a third above the bar.
What percentage of 1RM should I train at?
The table runs 60% to 95% because that covers most programmes: singles and doubles sit at 90% and up, sets of five commonly land near 80%, and higher-rep work drops into the 60s.