One rep max calculator
Enter a weight and the reps you got with it to estimate your one-rep max — plus the loads for every training percentage, rounded to plates you can actually put on the bar.
Enter the weight and reps of a hard set to estimate your max.
Now — is that number any good?
Benchmark places a lift against 1.8 million judged lifts from sanctioned powerlifting meets, for your bodyweight and sex, and tracks how your percentile moves over time. Bench press is free; no account, no workout logging.
One-rep max, answered
How is a one-rep max calculated from reps?
With a formula that converts a set of several reps into the single heaviest rep it implies. The two most used are Epley (weight × (1 + reps ÷ 30)) and Brzycki (weight × 36 ÷ (37 − reps)). They agree closely at low reps and drift apart as reps climb, so this calculator shows both and uses their average as the estimate. 100 kg for 5 reps works out to about 115 kg.
How accurate is an estimated 1RM?
Usually within a few percent when the set was hard and between 1 and about 10 reps. Above 10 reps the formulas lose accuracy fast, which is why this calculator stops at 12. The estimate also assumes the set was close to failure — a comfortable set of 5 underestimates what you can lift.
What are the percentages of 1RM used for?
Most strength programs prescribe loads as a percentage of your max: roughly 85–95% for heavy sets of 1–5, 70–85% for sets of 6–12, and 60–70% for lighter volume or technique work. The table rounds each load to the nearest 2.5 so it can be loaded with standard plates.
Is it safe to test a true one-rep max?
It can be, with a proper warm-up, good technique, a spotter or safety bars, and enough training behind you. Many lifters test rarely and estimate in between — a heavy set of 3–5 tells you nearly as much with far less risk. If you are new to lifting or have an injury, estimating is the better choice.