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One-Rep Max Calculator

Estimate your one-rep max from the weight and reps of a recent hard set.

Use 1–10 reps completed close to your limit with good form. Easier sets may underestimate your max.

Estimated one-rep max116.7 kg

An estimate, not a tested maximum or a weight you should attempt.

Include the bar for barbell lifts. For dumbbells, use the weight of one dumbbell.

Switching between kg and lb converts your weight automatically.

Percentages of Your Estimated 1RM
PercentageReference load (kg)
60%70
70%81.7
80%93.3
90%105

Reference loads only—not recommended attempts or guaranteed rep counts.

How It Works

For 2–10 reps, we use the Epley formula:

Estimated 1RM = weight × (1 + reps ÷ 30)

For one rep, we show the weight you lifted instead of applying the formula. A comfortable single does not tell you your maximum.

Know the Limits

Your 1RM is the most weight you can lift once for a particular exercise. Results vary with your technique, fatigue and experience, so use each estimate only for the lift you entered. We limit this tool to 10 reps to avoid less reliable high-rep estimates, but no rep range guarantees accuracy.

Use this as a training reference, not a prescription. Keep good form and seek qualified guidance before testing a maximal lift.

Know your set’s RPE? Try the separate RPE calculator.

Sources

  • Epley equationWikipedia lists weight × (1 + reps / 30) for more than one rep.
  • Practical 1RM guidance (NASM)Good-form effort, exercise specificity and ballpark estimates; NASM uses a different formula divisor.
  • Reynolds et al. (2006)The study’s own regression models favored lower-rep predictions for bench press and leg press. This is not a validation of Epley for every lift.

Denis Andrašec

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