1RM Calculator

Estimate your one rep max (1RM) from a submaximal lift. Enter the weight you lifted and the number of reps completed.

kg lb

Weight Lifted:

Reps Completed:

How It Works

The One Rep Max (1RM) is the maximum weight you can lift for a single repetition of a given exercise. Rather than attempting a dangerous maximal lift, you can estimate your 1RM from a submaximal set.

This calculator uses several established formulas and averages the results:

Formulas Used

Formula	Equation	Best For
Epley	`w × (1 + r/30)`	General use, most popular
Brzycki	`w × 36 / (37 - r)`	Lower rep ranges (1-10)
Lombardi	`w × r^0.10`	General use
Mayhew	`100 × w / (52.2 + 41.9 × e^-0.055r)`	Bench press
O'Conner	`w × (1 + r/40)`	General use
Wathan	`100 × w / (48.8 + 53.8 × e^-0.075r)`	General use

Where w = weight lifted, r = reps completed, e = Euler's number (~2.718).

Tip: For the most accurate estimate, use a weight you can lift for 2-10 reps. Estimates become less reliable beyond 10 reps.

Percentage Chart

Once you know your 1RM, use these percentages to plan your training:

% of 1RM	Reps	Training Goal
100%	1	Max strength
95%	2	Strength / peaking
90%	3-4	Strength
85%	5-6	Strength / power
80%	7-8	Strength / hypertrophy
75%	8-10	Hypertrophy
70%	10-12	Hypertrophy
65%	12-15	Endurance / hypertrophy
60%	15-20	Muscular endurance
50%	20+	Warm-up / endurance

Embed This Util

You can embed this util on your own site as a widget. Adding ?embed=1 to the URL loads a compact version with just the tool itself; no header, menu, or documentation. Paste this snippet into your HTML:

Copy snippet Adjust the height to taste.

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