1 Rep Max Calculator
Calculate your one-repetition maximum (1RM) for weightlifting exercises based on the weight lifted and number of repetitions performed.
Published by:
isCalculator Editorial Team
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How to use this tool?
Follow these steps to estimate your one-rep max (1RM) using the Epley formula:
- Enter the weight lifted – Input the weight you used for the set (e.g., 100). The calculator accepts both kilograms (kg) and pounds (lbs); just use the same unit throughout.
- Enter the number of reps performed – Input how many repetitions you completed with that weight (between 1 and 30).
- Click "Calculate 1RM" – The calculator will display your estimated one-rep max and show the Epley formula used:
1RM = weight × (1 + reps/30).
Note: The result is rounded to one decimal place and will match the unit you entered (kg or lbs). Use this estimate to plan your training loads safely.
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Frequently Asked Questions
A 1 rep max (1RM) is the maximum amount of weight you can lift for one repetition of a given exercise.
This calculator uses the Epley formula: 1RM = weight × (1 + reps/30). It estimates your max based on a submaximal effort.
Yes, the formula works for compound lifts like bench press, squat, deadlift, etc., but it's most accurate for multi-joint movements.
