One Rep Max Calculator

Estimate your maximum lifting capacity (1RM) using 7 scientific formulas and check your strength standards.

Weight Lifted

Unit

Reps Performed

Strength Standards (Optional)

Gender

Lift / Exercise

Your Body Weight (lbs)

Estimated 1RM (Average)

259.9 lbs

Estimated Repetitions Table

Reps	Weight (lbs)	% 1RM	Training Zone
1	259.9	100%	Peaking
2	246.9	95%	Strength
3	241.7	93%	Strength
4	233.9	90%	Strength
5	226.1	87%	Strength
6	220.9	85%	Hypertrophy
7	215.7	83%	Hypertrophy
8	207.9	80%	Hypertrophy
9	200.1	77%	Hypertrophy
10	194.9	75%	Hypertrophy
11	187.1	72%	Endurance
12	181.9	70%	Endurance

Formula breakdown

Epley262.5 lbs

Brzycki253.1 lbs

Lombardi264.3 lbs

Mayhew267.8 lbs

O'Conner253.1 lbs

Lander255.8 lbs

Wathan262.3 lbs

How one rep max is estimated

A one-repetition maximum (1RM) is the heaviest weight you can lift for exactly one repetition. Since testing true 1RM is risky, strength coaches use submaximal formulas: lift a weight you can handle for 2–10 reps, then estimate 1RM mathematically.

This tool averages seven formulas — Epley, Brzycki, Lombardi, Mayhew, O'Conner, Lander, and Wathan — for a balanced estimate. The training zones indicate which adaptation (strength, hypertrophy, or muscular endurance) is targeted by lifting that specific percentage of your 1RM.

Built and maintained by Meet Shah · Last updated 1 August 2026

What this tool is used for

Estimating a one-rep maximum from a set at a lower weight.
Comparing the Epley and Brzycki estimates on the same set.
Setting training percentages from an estimated maximum.
Tracking strength progress without testing a true maximum.
Producing a figure to plan a training block around.

Frequently Asked Questions

Which formula does it use?: The common estimators — Epley, Brzycki and their relatives — which all fit a curve to reps-versus-percentage data. They agree closely at low reps and diverge above about ten, which is why a set of fifteen is a poor basis for the estimate.
How accurate is an estimate?: Good within one to five reps, unreliable beyond. Estimating from a set of three is usually within a few percent; estimating from a set of twelve depends heavily on your muscular endurance relative to strength, which the formulas cannot know.
Why estimate rather than test?: Because a true one-rep max attempt carries real injury risk, requires a spotter, and is fatiguing enough to disrupt a training week. A rep-max test at three to five reps gives most of the information at a fraction of the cost.
Does the estimate transfer between lifts?: Poorly. Deadlifts tend to produce fewer reps at a given percentage than bench press, because the loading pattern and fatigue profile differ. A formula fitted on one lift systematically over- or under-estimates on another, which is why lift-specific data is worth collecting.
How is the number actually used?: As the reference for percentage-based programming — working sets at 70–85% of it. That is the whole point: the estimate does not need to be exact, it needs to be consistent, so that a percentage means the same thing week to week.

Common errors and gotchas

Estimating from a high-rep set, where the formulas lose accuracy quickly past about five reps.
Comparing figures from different formulas, which can differ by several kilograms.
Treating the estimate as a tested maximum, which it explicitly is not.
Estimating from a set that was not taken close to failure.
Applying a figure from one lift to another, where the relationship differs.