One-Rep Max (1RM) Calculator: 7 Formulas, Rep Chart, Plates and Strength Level

Free one-rep max calculator: enter the weight and reps of a hard set to estimate your 1RM with seven formulas (Epley, Brzycki, Lander and more). Get a rep and percentage chart, training zones, a plate loader for the barbell, and your strength level for squat, bench, deadlift and overhead press.

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Optional: lift, body weight and rounding (for strength level and plates)
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Enter the weight and reps of a hard set (up to 10 reps is best) — or try an example:

How to calculate your one-rep max

Your one-rep max (1RM) is the heaviest weight you can lift once with good form. Testing it directly is tiring and risky, so this calculator estimates it from a harder set of several reps. Enter the weight and how many clean reps you did to near failure. For example, 100 kg for 5 reps gives an Epley estimate of 100 × (1 + 5 ÷ 30) = 116.7 kg, and the average of seven formulas is about 114 kg.

The formulas

How accurate is a 1RM calculator?

Within about 5% for sets of 1–10 reps, if the set was taken close to failure and with good technique. Accuracy falls beyond 10 reps because fatigue and endurance take over from pure strength, and it varies by lift (it is usually best for the bench press). Treat the result as a training guide and start your first heavy attempt a little under it.

Questions

What percentage of 1RM should I train at?
85–100% for strength (1–5 reps), about 67–85% for muscle growth (6–12 reps), and below 67% for endurance. See the zones table above.
How many reps is 80% of my max?
About 8 reps on average, though it varies by person and lift.
Is it safe to test a real 1RM?
Use a spotter or safety bars, warm up well, and be conservative. The estimate avoids most of that risk.
Is my data private?
Yes. Everything stays in this browser.

General information, not medical advice. Related: Calories Burned Calculator · Protein Intake Calculator · Body Fat Calculator

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