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One-Rep Max Calculator

Your estimated one-rep max from a set you've already done, and the loads to use for every rep range, with no need to test a true max.

Updated . An estimate for general education, not medical advice.

Your result

Fill in the fields and your result shows up here. Everything is worked out in your browser; nothing you type is sent to us.

How the estimate works

Enter the weight and the number of reps you finished with good form, taken close to failure. The headline number uses the Epley formula, the same one Dalia's coach uses when it reads a logged set and reports an estimated 1RM. The Brzycki formula sits beside it so you can see how much two published equations differ for your set.

Epley
1RM = weight × (1 + reps ÷ 30)
Brzycki
1RM = weight × 36 ÷ (37 − reps)
Load for a rep target
load = 1RM ÷ (1 + reps ÷ 30)

A single rep is its own max. Like the app, the calculator makes no estimate from more than 12 reps.

How accurate it is

Fewer reps give a better estimate. Brzycki wrote that the relationship stops being linear beyond about 10 reps, and limited his formula to sets of under 10. In a study of bench press in men, equations like these over- or under-predicted 1RM even among people doing 10 reps or fewer, with Brzycki the most accurate there. A set of 3 to 6 hard reps is the sweet spot.

The estimate also depends on the lift and the person. Trained lifters, untrained beginners, a squat and a curl all behave a little differently, so treat it as a starting point for choosing loads and adjust by feel.

Who this is wrong for

  • Beginners, whose strength climbs quickly as technique improves, so the estimate goes stale within weeks.
  • Sets of more than 10 reps, where every formula gets less reliable.
  • Anyone told to avoid heavy straining, for example during pregnancy or after recent surgery.

Talk to a clinician when

  • You have high blood pressure, heart disease, or a history of hernia or eye problems that heavy straining can worsen.
  • You feel chest pain, dizziness or sharp joint pain while lifting.
  • You are pregnant or postpartum and want to keep lifting heavy.

Read more

How to estimate your one-rep max without testing it

Sources

  1. Brzycki M. Strength testing: predicting a one-rep max from reps-to-fatigue. Journal of Physical Education, Recreation and Dance, 1993;64(1):88-90.
  2. Mayhew JL, et al. Muscular endurance repetitions to predict bench press strength in men of different training levels. Journal of Sports Medicine and Physical Fitness, 1995;35(2):108-113.

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This calculator gives an estimate for general education. It is not medical advice and it is not a substitute for care from a qualified clinician. Report an error to info@daliahealth.com.