1-Rep Max Calculator
Estimate your one-rep max from any weight and rep count using the Epley, Brzycki, and Lombardi formulas.
Estimated one-rep max
115.5 kg
Average of Epley, Brzycki, and Lombardi
Epley
116.7 kg
Brzycki
112.5 kg
Lombardi
117.5 kg
Training percentages
| % of 1RM | Weight |
|---|
These formulas are statistical estimates derived from average lifter data, not a measurement of your actual one-rep max — individual results vary, especially the further your rep count is from 1. They also lose accuracy above roughly 10-12 reps, which is why input is capped there. Always work up to a true 1RM attempt gradually and with a spotter if you intend to test it directly.
About this tool
How to use it
- Enter the weight you lifted and pick kg or lb.
- Enter how many reps you completed with that weight (capped at 12 — the formulas lose accuracy beyond that).
- Press Calculate 1RM, or just keep typing — the results update live.
- Use the training percentage table below to plan warm-up sets and working weights off your estimated max.
Why it matters
Testing a true one-rep max directly is fatiguing and carries injury risk, especially without a spotter. Estimating it from a lighter set you can complete safely — say 5 reps at a comfortable weight — lets you program percentage-based training (working at 70% or 85% of your max) without ever having to attempt the actual single lift.
When to use it
Useful when programming a strength cycle that's based on percentages of your max, when you want a rough max estimate without testing it directly, or when comparing your estimated progress across a training block using the same rep-test each time.
Good to know
Epley, Brzycki, and Lombardi are three independently published formulas, each a statistical fit to average lifter data rather than a physical law — they're shown separately, plus averaged, because they diverge from each other more as rep count increases, and no single one is universally 'more correct.' All three assume you performed the set close to failure; a set with reps left in reserve will underestimate your real max. Accuracy drops noticeably above roughly 10-12 reps, which is why the calculator caps the rep input there.
Common questions
Which formula is most accurate?
None of the three is universally best — each is a statistical fit calibrated on different lifter populations, and they tend to agree closely around 3-6 reps and diverge more the higher the rep count goes. Showing all three, plus their average, is more honest than picking one and presenting it as definitive.
Why is the rep count capped at 12?
These formulas are reasonably reliable for low-to-moderate rep sets (roughly 1-10), but the underlying relationship between reps and load breaks down at higher rep counts — some formulas (like Brzycki) become mathematically invalid entirely at 37 reps and increasingly unreliable well before that. Capping at 12 keeps the estimate in the range these formulas were actually built for.
Does this measure my actual one-rep max?
No — it's an estimate based on a lighter set, not a direct measurement. Your actual 1RM depends on factors these formulas can't see (technique, fatigue that day, how close to failure your set really was), so treat the result as a planning number, not a guarantee.
What is the training percentage table for?
Many strength programs prescribe working weights as a percentage of your 1RM (e.g. 'work up to 3 sets at 80%'). The table converts your estimated max into the actual weight for each common percentage, so you don't have to do that arithmetic mid-workout.
Should I use this instead of testing my real 1RM?
For most training purposes, yes — an estimate from a safer, lower-rep set avoids the fatigue and injury risk of a maximal single-rep attempt. If you do want to test your actual 1RM, work up to it gradually in small increments with a spotter present.