How do I calculate my bench press 1RM?

Enter a weight you can lift for 2–10 reps. The Epley formula estimates your 1RM as: weight × (1 + 0.0333 × reps). Use a recent, near-maximal set for the most accurate result.

Which rep range gives the most accurate 1RM estimate?

Sets of 3–5 reps give the most accurate estimates. As rep counts increase above 8–10, the formulas become less reliable because endurance factors influence performance more than maximal strength.

Should I attempt my calculated 1RM?

1RM formulas are estimates. Treat the result as a guide for training percentages rather than a weight to attempt immediately. If you want to test your true 1RM, follow a proper peaking protocol with a spotter.

Is my data sent to a server?

All calculations are pure JavaScript running in your browser. Our servers are not involved at any point.

Bench press one rep max calculator

Enter the weight you lifted and the number of reps to estimate your bench press one rep max (1RM). Uses the Epley and Brzycki formulas and shows a full percentage table for programming your training loads.

Exercise

Weight lifted (kg)

Reps performed (1–12)

How it works

Two formulas are used and averaged. The Epley formula (1985): 1RM = weight × (1 + 0.0333 × reps). The Brzycki formula (1993): 1RM = weight × 36 / (37 − reps). Both assume a near-maximal set of 1–12 reps. The percentage table divides the estimated 1RM by each percentage to give your working weight for that intensity zone. All arithmetic runs locally in your browser.

Processing runs in your browser

All calculations happen locally using pure JavaScript. Our servers are not involved at any point.

Technical specification

The Epley formula was published by Boyd Epley (1985) and remains the most widely used 1RM estimator in strength and conditioning. The Brzycki formula was published by Matt Brzycki in Strength & Conditioning Journal (1993). Both are population-average models with a standard error of approximately ±3–5 kg on sets of 3–5 reps. Accuracy decreases above 10 reps as aerobic capacity increasingly influences performance.

Epley formula: weight × (1 + 0.0333 × reps)
Brzycki formula: weight × 36 / (37 − reps)
Valid rep range: 1–12 reps (accuracy decreases above 8)
Browser API: Pure JavaScript arithmetic. No library

Related operations

For estimating daily energy needs for a training plan, try the calorie calculator. To track fat-free mass between training blocks, use the lean body mass calculator. For setting cardio targets alongside strength work, see the heart rate calculator.

Frequently asked questions

How do I calculate my bench press 1RM?: Enter a weight you can lift for 2–10 reps. The Epley formula estimates your 1RM as: weight × (1 + 0.0333 × reps). Use a recent, near-maximal set for the most accurate result.
Which rep range gives the most accurate 1RM estimate?: Sets of 3–5 reps give the most accurate estimates. As rep counts increase above 8–10, the formulas become less reliable because endurance factors influence performance more than maximal strength.
Should I attempt my calculated 1RM?: 1RM formulas are estimates. Treat the result as a guide for training percentages rather than a weight to attempt immediately. If you want to test your true 1RM, follow a proper peaking protocol with a spotter.
Is my data sent to a server?: All calculations are pure JavaScript running in your browser. Our servers are not involved at any point.

Last reviewed May 26, 2026