1RM Calculator
Estimate your one-repetition maximum from a weight and repetition set, then view useful training percentages for your next workout.
How to use this calculator
Follow these three steps to create your estimated one-repetition maximum.
Enter your lifted weight
Use the weight you lifted for a challenging set.
Enter your repetitions
Use the number of clean repetitions completed with good form.
Use the result carefully
Apply the estimate as a planning guide, not a guaranteed maximum.
Estimate your 1RM
Enter a recent set and choose the formula you want to use.
Set information
For best results, use a set completed close to technical failure, usually within 2–10 repetitions.
Your estimated 1RM
Use this number as a training reference rather than a guaranteed maximum.
| Percentage | Suggested load |
|---|
How the result was calculated
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How to interpret this result
Estimated 1RM values are useful for planning and tracking, but they can vary by exercise, technique, fatigue, and experience.
What is a 1RM?
Your one-repetition maximum, or 1RM, is the heaviest load you can lift once with proper technique for a specific exercise.
Actual 1RM
An actual 1RM is determined by gradually increasing the load until one technically sound repetition is completed.
Estimated 1RM
An estimated 1RM uses a lighter weight and the number of repetitions completed to predict your maximum strength.
1RM formulas explained
Different equations can produce slightly different results. For progress tracking, use the same formula each time.
Epley formula
A practical formula commonly used for moderate repetition sets.
This is the default formula on this page.
Brzycki formula
Often used for lower-repetition sets of up to 10 repetitions.
Avoid using this equation for high-repetition sets.
Lombardi formula
An alternative equation that can be compared with other estimates.
Formula choice can depend on the exercise and training population.
Why results differ
Bench press, squat, deadlift, machines, and isolation exercises can produce different prediction accuracy. Fatigue, range of motion, tempo, and form also affect the estimate.
Tips for better 1RM estimates
Consistency is more valuable than chasing a perfect number.
Count only repetitions completed with controlled, repeatable technique.
Sets of roughly 2–10 repetitions are generally more useful for prediction.
Compare the same movement, equipment, range of motion, and setup.
Use gradual warm-up sets before heavy training or testing.
Training percentages are starting points that may need adjustment.
Use a spotter or qualified coach when lifting near your maximum.
1RM Calculator FAQs
Answers to common questions about one-repetition maximum calculations.
