One Rep Max (1RM) Calculator
Enter a weight and the reps you did to estimate your one-rep max (1RM). We show both the Epley and Brzycki estimates plus a percentage table so you can program every set.
Your results
| 95% | 109 kg |
| 90% | 104 kg |
| 85% | 98 kg |
| 80% | 92 kg |
| 75% | 86 kg |
| 70% | 81 kg |
| 65% | 75 kg |
| 60% | 69 kg |
How it works
- 1Your 1RM is estimated from the weight and reps of a hard set using the Epley and Brzycki formulas.
- 2Estimates are most accurate under about 10 reps; higher reps introduce more error.
- 3Use the percentage table to load your working sets (for example 5x5 at ~80%).
Frequently asked questions
How is one-rep max calculated?
It is estimated from the weight and repetitions of a submaximal set. The Epley formula (weight x (1 + reps/30)) and Brzycki formula are the two most common, and averaging them is reliable under 10 reps.
How accurate is a 1RM estimate?
Very accurate for sets under about 6 reps, and still useful up to 10. Beyond 10 reps, differences in endurance make the estimate less reliable.
Should I test my true 1RM?
Rarely. An estimated 1RM from a calculator is safer and good enough to set training percentages. Save true max attempts for competitions or occasional testing with a spotter.
Using the result
What the number is
An estimate from a formula: rep-max equations for strength, even-pace arithmetic for running, MET values for calories burned. It describes an average performer, so your own number can sit noticeably above or below it.
How to use it
Use it to pick training weights or paces, plan sessions and compare like with like over time. Retest under similar conditions every few weeks instead of relying on one estimate forever.
When to stop guessing
If your numbers have stalled for several weeks, the fix is usually in programming, recovery and consistency rather than in the calculator. That is what a coach on Trainera builds with you.
What this calculator cannot know
This calculator does not know your technique, fatigue, sleep, terrain, weather, heart rate or training history, and all of them change real performance and energy use. Estimates are least reliable at the edges: sets of more than ten reps, very long races and unusual activities. Warm up properly, test maximal lifts with a spotter, and check with a doctor before hard training if you have a heart condition or another health concern. Nothing here is medical advice.
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Turn these numbers into a real plan
Train on your own with Trainera's free workout and diet tracker, or get matched with a certified personal trainer who builds your plan around these numbers.