One-Rep Max Calculator
Estimate your one-rep max from a recent set — no max-out attempt needed — plus the training weights for common rep ranges.
Strength training apps and programs
Learn moreEstimate without maxing out
Testing a true one-rep max is risky and taxing, so lifters estimate it from a lighter set taken near failure. Your 1RM then anchors training: most programs prescribe a percentage of 1RM for a given rep range, so knowing the number lets you load the bar correctly.
How it’s calculated & sources
We use the Epley formula: 1RM = weight × (1 + reps ÷ 30). The percentage table shows typical training loads for 2 to 12 reps.
Benchmark: the Epley formula — accurate for sets under about 10 reps; accuracy drops as reps climb.
Results update as you type and are general estimates, not personalized financial, tax, medical or legal advice. Verify with a professional.
Worked example
Lifting 185 lb for 5 reps estimates a 1RM of about 216 lb — so roughly 173 lb for a set of 8 (80%).
Frequently asked questions
How many reps should I use?
Fewer reps (3–6) give the most accurate estimate. High-rep sets understate your true max because fatigue dominates.
Should I actually attempt my 1RM?
Only with experience, a spotter and proper warm-up. The estimate is safer for programming and works well for most lifters.