🏋️One Rep Max Calculator

Estimate your one-rep max from the weight and reps of a set.

Weight Lifted

Reps Performed

About One Rep Max Calculator

Your one-rep max (1RM) is the maximum weight you can lift for a single repetition of any exercise, and it's the gold standard for measuring absolute strength. This calculator estimates your 1RM from a submaximal set — for example, the weight you can lift for 5 or 8 reps — using the Epley and Brzycki formulas. It also generates a full percentage-based training table so you can immediately apply your 1RM to a structured strength program.

How to Use One Rep Max Calculator

1
Enter the weight and reps
Input the load you used and how many reps you completed in that set — ideally a set of 3–8 reps taken close to failure.
2
View your estimated 1RM
The calculator returns your estimated one-rep max using the Epley and Brzycki formulas.
3
Use the percentage table
Reference the full 1RM percentage breakdown to set training loads for your program (e.g., 80% for 4x6).

Common Use Cases

Setting training loads for a powerlifting or strength program like 5/3/1 or Starting Strength
Tracking strength progress over months without repeated max testing
Comparing relative strength across different exercises
Calculating accessory lift weights based on a percentage of main lift 1RM

Frequently Asked Questions

How accurate are one-rep max calculators?

1RM estimates are most accurate when based on sets of 3–6 reps. As rep counts increase above 10, formula accuracy decreases because endurance factors play a larger role. For the best estimate, test with a weight you can lift 3–5 times with good form rather than using a very light weight for 15+ reps.

Should I actually test my one-rep max?

True 1RM testing carries a higher injury risk, especially for beginners. For most people, estimated 1RM from submaximal testing is both safer and sufficient for programming purposes. Reserve true 1RM testing for powerlifting meets or advanced strength assessments conducted with a spotter.

How do I use my 1RM to program workouts?

Most strength programs prescribe loads as a percentage of 1RM. Common benchmarks: 85–95% for heavy strength work (1–3 reps), 75–85% for hypertrophy (6–10 reps), 65–75% for volume work (10–15 reps), and below 65% for technique and endurance. Your 1RM training table makes these calculations instant.