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 numbers are
An estimate for an average person with your stats. Formulas like Mifflin-St Jeor are accurate to roughly plus or minus ten percent for most people, which is close enough to start and never close enough to argue with the scale.
How to use them
Eat at the calculated intake for two to three weeks and weigh yourself consistently. If the trend is not moving the way you want, adjust the intake by a few hundred calories rather than recalculating from scratch.
When to stop guessing
If you have been adjusting for months without progress, the missing piece is usually programming and accountability rather than a better number. That is what a coach on Trainera does.
What this calculator cannot know
Every formula here works from height, weight, age, sex and activity, which is most of the picture and not all of it. It does not know your training history, your medication, your thyroid, how well you sleep, how much you actually move outside training, or how honestly you log food. Treat the output as a starting estimate: pregnant and breastfeeding women, children, competitive athletes at very low body fat and anyone managing a medical condition should get a number from a doctor or dietitian instead of from a form. 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.