What this tool does
You enter a lift, the load, and how many clean reps you did. The page averages Epley and Brzycki and shows common percentages for 5×5 and heavy triples.
How it works
Epley: 1RM = w × (1 + reps/30). Brzycki: 1RM = w × 36 / (37 − reps). We average them and refuse to treat a 15-rep pump set as a max.
Formula and methodology
Epley (1985): w×(1+r/30). Brzycki (1993): w×36/(37−r). Displayed 1RM is the mean. For r = 1 the estimate is the weight itself.
How to interpret the result
A 5-rep set at 100 kg often estimates a 1RM near 115–120 kg. If you grind ugly reps, the estimate is high. If you had three reps left, it is low.
Example
Bench 80 kg × 5: Epley 93.3, Brzycki 90.0, average ~91.7 kg. 80% for volume work is about 73 kg.
Common mistakes
- Using a sloppy last rep that would not have counted in a meet.
- Estimating from 12+ reps — the curves were not built for that.
- Jumping to the predicted single the same day you are tired.
When this estimate may be off
- New lifters whose technique fails before strength.
- Machines with different strength curves than a barbell.
- You need a sanctioned meet result — this is homework math.