Free THRYV tools
One-rep max calculator
Estimate your one-rep max from the weight and repetitions in a completed set. Compare Epley and Brzycki, in kilograms or pounds.
Estimated one-rep max
93.3kg
80 kg × 5 reps · Epley
A reference estimate, not a measured maximum or a recommended attempt.
Percentages of your estimate
Reference values from the Epley result. These are not personalised training loads.
How to calculate your estimated one-rep max
- Choose kilograms or pounds and enter the total weight lifted. For a barbell lift, include the bar.
- Enter the repetitions completed in a single set, using the same technique throughout.
- Compare the two estimates. For a set of 80 kg for 5 repetitions, Epley gives 93.3 kg and Brzycki gives 90 kg.
Use the total load consistently. If you normally record each dumbbell separately, keep using that convention when comparing sets. A machine’s labelled resistance is only comparable with the same machine and setup.
The Epley and Brzycki formulas
With w as the lifted weight and r as completed repetitions:
- Epley
1RM = w × (1 + r ÷ 30)- Brzycki
1RM = w × 36 ÷ (37 − r)
For one completed repetition, this tool returns the weight you lifted for both formulas. Results round to one decimal place, while percentage calculations use the unrounded estimate.
What an estimate can tell you
An estimated 1RM can make different sets easier to compare. Keep the exercise, equipment, technique and formula consistent, and look at the pattern over time. Sleep, recent training and how many repetitions you had left can all change what a set means.
A study of bench press and leg press testing found five-repetition tests more predictive than ten- or twenty-repetition tests in its study group. That does not make any formula exact for every person or exercise. Read the original study by Reynolds and colleagues.
Want to keep the context alongside the numbers? Explore THRYV’s strength training features and our guide to combining running with strength.
Formula references
Epley, B. (1985), Poundage Chart, in Boyd Epley Workout, p. 86. Brzycki, M. (1993), Strength Testing—Predicting a One-Rep Max from Reps-to-Fatigue, Journal of Physical Education, Recreation & Dance, 64(1), 88–90.
Common questions
What is a one-rep max?
A one-repetition maximum, or 1RM, is the most weight you can lift once for a particular exercise with the intended technique. This calculator estimates that value from a set of repetitions; it does not measure it.
Should I use Epley or Brzycki?
Both are commonly used estimates, and neither is guaranteed to match your lift. Compare the two, then use the same formula when following your own progress. The result depends on the exercise, technique and how close the set was to your repetition limit.
How many repetitions should I enter?
Enter the repetitions you completed in one set, from 1 to 12. A lower-repetition set close to your repetition limit is generally more useful for estimating maximum strength than a long set. If you could have done several more repetitions, these formulas may underestimate your capacity.
Can I use the result as my next lifting weight?
The number is an estimate for reference, not a recommended attempt. It does not account for your experience, technique, fatigue or equipment. The percentage table is arithmetic based on the estimate, rather than a personalised training prescription.
Is the calculator free, and do I need an account?
It is free to use without a THRYV account. Your weight and repetitions are calculated in this browser and are not saved to a THRYV profile.