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One Rep Max Calculator
Estimates 1RM from a submaximal set using Epley or Brzycki. Educational only—not a prescription to attempt a maximal lift.
Limitation: Educational estimate only.
How to Estimate 1RM
Use a set you completed with good form and a known load.
Enter the weight you lifted.
Prefer lower-rep sets
Estimates from 2–6 hard reps are usually more stable than long sets near failure.
What the Estimated 1RM Means
It is a formula projection from the set you entered, not a measured maximal lift.
1RM Estimation Examples
Epley from 5 reps
Entered set
Estimated one-rep max
100 × (1 + 5/30) = 116.666… → 116.7.
Brzycki from 5 reps
Entered set
Estimated one-rep max
100 × 36 / (37 − 5) = 112.5.
Use estimates for percentages
Program with estimated 1RM percentages instead of grinding unexpected max attempts.
Frequently Asked Questions
Still have questions about this calculation?
Try the CalculatorOne-Rep Max Formulas
No velocity or RPE models are embedded.
Formula
Epley
1RM = weight × (1 + reps / 30)
Brzycki
1RM = weight × 36 / (37 − reps)
Scientific Background
Assumptions: the set represents true performance under the chosen formula. Limitations: fatigue, exercise selection, and technique change real 1RM. CDC physical-activity guidance emphasizes progressive, safe training rather than maximal testing for most adults.
Sources & review
One Rep Max Calculator documents the references behind its formulas and assumptions. Always treat results as educational estimates, not personalized professional advice.
Last reviewed
July 22, 2026
Physical Activity Guidelines for Adults
Centers for Disease Control and Prevention (CDC)
https://www.cdc.gov/physical-activity-basics/guidelines/adults.html
See our methodology and corrections policy.