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One Rep Max Calculator
Your one-rep max (1RM) is the heaviest weight you can lift once with good form. This calculator estimates it from a lighter set so you can plan training loads without testing a risky maximum lift.
About the One Rep Max Calculator
Your one-rep max (1RM) is the heaviest weight you can lift once with good form. This calculator estimates it from a lighter set so you can plan training loads without testing a risky maximum lift.
How to use the One Rep Max Calculator
- Enter the Weight Lifted and the number of Repetitions you completed with good form.
- Press Calculate 1RM to see your estimated max and an intensity table showing 90, 80, 70 percent and lower.
Formula and method
Epley formula: 1RM = weight × (1 + reps ÷ 30)
Worked example
Lifting 100 kg for 5 reps gives 100 × (1 + 5 ÷ 30) = 116.7 kg. Working at 80 percent would be about 93 kg.
Tips
- Estimates are most accurate for sets of 10 reps or fewer.
- Always warm up and use a spotter or safety bars on heavy lifts.
- Use the percentage table to plan strength (85 to 95 percent), hypertrophy (65 to 80 percent) and endurance work.
Frequently asked questions
Is a calculated 1RM the same as a tested 1RM?
It is an estimate. Technique, fatigue and the exercise itself can shift the real number by several percent.
Which lifts does this work for?
It works for common barbell and machine lifts such as squat, bench press and deadlift.