QuickCalculators estimates one rep max from weight and reps using Epley, Brzycki or Lombardi formulas, compares all three, and prints a percentage reference table. The one rep max calculator caps reps at ten because accuracy fades beyond that range, and labels estimates with roughly plus or minus ten percent error.
Estimate a one rep max from a weight and rep count
Enter weight in kilograms or pounds, reps between one and ten, and pick a formula. At one rep, each formula returns the entered weight within rounding. Five reps at 100 kilograms on Epley yields about 116.7 kilograms estimated max.
Compare the Epley, Brzycki and Lombardi formulas
Epley uses 1RM equals w times (1 plus r over 30). Brzycki uses w times 36 over (37 minus r). Lombardi raises reps to the 0.10 power on weight. All three appear side by side so you can see spread on the same set.
Read the percentage training table
The table lists loads from 100 percent down to 50 percent of the estimated max with percentages labeled as reference, not a programme. Values scale linearly from the chosen formula result. Use the table to translate between estimated max and submaximal weights.
Understand how accurate the estimate is
Submaximal estimates carry about plus or minus ten percent error depending on lifter, lift type and rep count. Treat the output as planning data, not a weight to attempt cold. A spotter belongs in the room for any true one-rep test.
Why the calculator caps the rep count at 10
Brzycki grows unstable as reps approach thirty-seven in the denominator, and all formulas widen error past ten reps. The cap keeps inputs in the range where linear-style formulas were fit. Higher reps need different testing methods.
Avoid this common mistake
Athletes treat the estimated max as a target to load on the bar today. The number is a statistical guess with about ten percent error. Use submaximal work unless you deliberately test with proper safety, including a spotter on bench and squat attempts.
Frequently asked questions
What is a one rep max?
A one rep max is the heaviest weight a person can lift once with good form for a given exercise. The one rep max calculator estimates it from submaximal sets.
What is the Epley formula?
The Epley formula estimates 1RM as weight times (1 plus reps divided by 30). QuickCalculators applies it when you select Epley on the form.
Which 1RM formula is most accurate?
No single 1RM formula is most accurate for every lifter; Epley, Brzycki and Lombardi differ slightly on the same inputs. Compare all three rows before picking one for tracking.
How accurate is an estimated one rep max?
An estimated one rep max is typically within about plus or minus ten percent of a true test, wider at high rep counts. Fewer reps usually tighten the guess.
Why do fewer reps give a better estimate?
Fewer reps give a better estimate because fatigue and technique breakdown affect formulas less at low rep counts. That is why input caps at ten reps.
Is a one rep max the same for every exercise?
A one rep max is not the same for every exercise; bench, squat and deadlift each need separate tests or estimates. Enter weights for the lift you actually performed.
What percentage of 1RM should you train at?
Training percentages depend on goals and programming outside this page. The table lists reference percentages only; it does not prescribe sets or progression.
Summary
QuickCalculators estimates 1RM with Epley, Brzycki and Lombardi from weight and one to ten reps, shows all three values, and prints a labeled percentage table. Expect roughly ten percent error, use a spotter for true max tests, and treat the table as reference data rather than a workout plan. Enter lift weight and reps, read estimates, compare formulas.