One Rep Max Calculator: your max, done right.
Not by guesswork.
Enter your weight and reps: the weighted average of 3 scientific formulas gives you your theoretical max, with no risky max-out test.
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1RM, RM, %1RM: decoded.
Your 1RM (one-rep max, or one-repetition maximum) is the heaviest load you can lift once on a given exercise with clean form. It's the reference unit for maximal strength in the gym.
By extension, an nRM is the max load for n reps (your 10RM = the weight you can lift only 10 times). Percentages of 1RM (%1RM) are then used to program your loads by goal: strength, hypertrophy, endurance. This calculator estimates your 1RM from a sub-maximal set, with no risky max-out test.
Your load table, by % of 1RM
Click a zone or a row to apply it straight to the calculator.
One number,
four training
decisions.
Your 1RM is not just an ego score. It is the base every training intensity is set from.
Every set as a % of your 1RM: you know exactly what load to use for strength, hypertrophy or endurance.
A stable benchmark over time. Compare your estimated maxes from one cycle to the next, with no max-out test.
No need to chase a true max every session. You drive the load from a submaximal set instead.
Squat, bench, deadlift: place each lift against your bodyweight and balance your program.
Brzycki, Epley, Lombardi the science behind .
Edit the weight or reps right inside the formulas: the result recalculates live.
The coaches' reference. Especially accurate between 3 and 10 reps.
The best known. Linear, reliable across a wide rep range.
A power model. Holds up well on long sets.
Sources & formulas
Estimates rely on three validated scientific formulas, averaged together to smooth out their differences:
- Epley (1985) : estimating the 1RM from the number of repetitions.
- Brzycki (1993) : 1RM prediction, especially reliable from 3 to 10 repetitions.
- Lombardi (1989) : a power formula suited to high-rep sets.
- LeSuer et al. (1997) : comparative study validating the accuracy of these formulas.
Strength standards: StrengthLevel (over 48 million performances), cross-checked with ExRx.
Why this calculator ?
Seven criteria, three calculators. Click a row to see the feature.
Before testing your true 1RM
Warm up properly. Mobility, progressive sets, muscle activation. Never cold.
A spotter or safety bars. Never attempt a true max alone, without a spotter or a safety rack.
Technique before load. If form breaks down, the rep does not count. Stop before something gives.
Not every session. A true strength test belongs every 8 to 12 weeks, not every week.
Everything people ask us
What exactly is a 1RM?
Should I test my true 1RM or estimate it?
Which formula is the most accurate?
How many reps should I use for a good estimate?
Is the 1RM different per exercise?
How often should I recalculate my 1RM?
With 14 years of bodybuilding practice and a background as a military instructor, I'm now the founder of Fit'Distance. Passionate about sports performance optimization and entrepreneurship, I create tools to help sports coaches grow their business and help their clients progress intelligently.
Calculate your 1RM here.
Program everything else there.
Fit'Distance turns your maxes into automatic programs, tracking and intensities for your clients.