Health Calculator
1 Rep Max Calculator
Estimate your one rep max with four widely used formulas, compare the spread, and turn the result into practical training weights.
What this 1RM calculator helps you do
Estimated one rep max values are useful when you want to program strength work without testing a true max every week. This page gives you a fast range instead of a single opaque number.
How the formulas differ
Epley is a common default for moderate rep ranges. Brzycki often stays tighter at low reps. Lombardi can run higher as reps increase, while O'Conner gives a more conservative estimate. Comparing all four helps you spot outliers.
How to use the result
After you calculate, use the training table to find common working percentages for triples, sets of five, and volume work. If you are fatigued, use the lower end of the range rather than chasing a gym PR.
Safety note
Estimated maxes are useful, but they are still estimates. Warm up properly, use a spotter when appropriate, and avoid maximal attempts when your technique is breaking down.
Frequently Asked Questions
How accurate is a 1 rep max calculator?
It is usually close enough for programming, especially between 1 and 10 reps, but it is still an estimate. Technique, fatigue, and lift selection all affect the final number.
Why does each formula give a different result?
Each formula models fatigue differently. That is why comparing several outputs gives a better sense of the realistic range for your current strength.
Should beginners test a real one rep max?
Most beginners are better off using an estimated max from a clean set of 3 to 8 reps instead of forcing a true single.
Can I switch between pounds and kilograms?
Yes. The calculator keeps the output in the same unit you select for the lift.