The maximum weight you can lift for a single repetition of an exercise.

How is 1RM estimated?

From submaximal lifts using formulas like Epley and Brzycki, which model the weight–rep relationship.

Why use a percentage table?

Training programs prescribe loads as a percentage of 1RM; the table gives you each working weight.

Yes. Your lift weights and reps are used only in your browser to estimate your one-rep max; nothing is uploaded.

How accurate is an estimated one-rep max?

Estimates are most accurate in the 1 to 10 rep range, typically within a few percent of a true max. Above 10 reps the weight-to-rep relationship becomes less linear, so accuracy drops. Using a set you complete with good form gives the best estimate.

Epley vs Brzycki — which formula is better?

Both are well established. Epley (weight multiplied by (1 + reps/30)) tends to give slightly higher numbers at high reps, while Brzycki gives slightly lower. Averaging the two, as this tool does, reduces formula-specific bias for programming.

How do I use my 1RM to set training weights?

Multiply your 1RM by the target percentage: about 85 to 95% for strength (2 to 4 reps), 67 to 75% for hypertrophy (8 to 12 reps) and 50 to 67% for endurance. The percentage table does this automatically so you can load the bar without mental maths.

One Rep Max Calculator (1RM)

How to use One Rep Max Calculator

The one-rep max (1RM) calculator estimates the maximum weight you could lift for a single repetition of any exercise, based on a submaximal set of weight and reps. Two formulas are computed — Epley and Brzycki — and their average is displayed to give a more robust estimate. A full percentage training table from 50% to 100% of your 1RM shows the working weight for each intensity zone, which is the cornerstone of percentage-based strength programming.

Select your weight unit (kg or lbs).
Enter the weight you lifted (e.g. 100 kg).
Enter the number of repetitions you completed before failure or near-failure (1–36).
Click Calculate 1RM to see Epley, Brzycki and average estimates.
Use the percentage table to find your working weights for training sets at any intensity.

Your data never leaves your device — 100% private processing.

Epley vs Brzycki: which formula to use?

The Epley formula (1985) calculates 1RM = weight × (1 + reps ÷ 30) and is among the most widely cited. The Brzycki formula (1993) calculates 1RM = weight ÷ (1.0278 − 0.0278 × reps) and tends to give slightly lower estimates, particularly at higher rep counts. Both formulas are more accurate in the 1–10 rep range; accuracy degrades above 10 reps because the weight–rep relationship is not perfectly linear. Using the average of both reduces formula-specific bias and is generally preferred for programming purposes.

Epley vs Brzycki formula comparison
Formula	Year	Equation	Best range
Epley	1985	weight × (1 + reps/30)	1–10 reps
Brzycki	1993	weight / (1.028 − 0.028 × reps)	1–10 reps
Average	—	Mean of Epley and Brzycki	1–10 reps (recommended)

Using the percentage table for strength programming

Most strength programs prescribe loads as a percentage of 1RM. At 80–85% 1RM (3–6 reps), you train the strength-hypertrophy continuum. At 70–80% (6–12 reps), hypertrophy is maximised. At 85–95% (1–5 reps), you develop maximum strength. Olympic lifters and powerlifters often train at 85–100% in peaking phases. The percentage table gives you the actual kilogram or pound target for each zone, eliminating mental arithmetic between sets.

Training intensity zones by % of 1RM
% of 1RM	Rep range	Primary adaptation
95–100%	1–2	Max strength (neural)
85–95%	2–4	Strength
75–85%	4–8	Strength-hypertrophy
67–75%	8–12	Hypertrophy
50–67%	12–20+	Muscular endurance

Worked examples

5 reps at 100 kg

Inputs: Epley: 100 × (1 + 5/30)

Result: ≈ 117 kg estimated 1RM

8 reps at 80 kg

Inputs: Epley: 80 × (1 + 8/30)

Result: ≈ 101 kg estimated 1RM

Working weight at 80%

Inputs: 1RM 117 kg × 0.80

Result: ≈ 94 kg for strength sets

Glossary

1RM: One-Rep Max — the maximum weight you can lift for exactly one full repetition.
Epley formula: A 1985 equation estimating 1RM from submaximal reps: weight × (1 + reps/30).
Brzycki formula: A 1993 equation estimating 1RM: weight / (1.028 − 0.028 × reps).
Training volume: Sets × reps × weight — a key driver of hypertrophy and strength gains.
RPE: Rate of Perceived Exertion — a subjective scale (1–10) used alongside percentage training to auto-regulate intensity.

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One Rep Max Calculator

How to use One Rep Max Calculator

Epley vs Brzycki: which formula to use?

Using the percentage table for strength programming

Worked examples

Glossary

Related reading

Frequently Asked Questions

Why use One Rep Max Calculator?

Common use cases

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