What is the Epley formula?

Epley 1RM = weight × (1 + reps ÷ 30). It is one of several accepted formulas; accuracy decreases for sets above 10 reps.

Is the estimated 1RM accurate?

It is an estimate. Studies show Epley is accurate to within ~5% for sets of 1–10 reps. For very high rep sets (15+) accuracy drops — use sets of 3–8 for best results.

One-Rep Max Calculator

Estimate your 1RM one-rep max from any set of reps and weight using the Epley formula.

Embed this tool on your site

<iframe src="https://abracalc.com/calculator/one-rep-max-calculator/embed.html" width="340" height="320" style="border:1px solid #e4e7ec;border-radius:12px" loading="lazy"></iframe>

How to use this tool

Enter weight lifted and reps performed in the fields above.
Results update instantly as you type — or click Calculate.
Read your estimated 1rm and the full breakdown beneath it.

The Epley formula estimates your one-repetition maximum from any multi-rep set. Use this to track strength progress without maxing out every session.

Frequently asked questions

What is the Epley formula?: Epley 1RM = weight × (1 + reps ÷ 30). It is one of several accepted formulas; accuracy decreases for sets above 10 reps.
Is the estimated 1RM accurate?: It is an estimate. Studies show Epley is accurate to within ~5% for sets of 1–10 reps. For very high rep sets (15+) accuracy drops — use sets of 3–8 for best results.

References & sources

Wikipedia: One-repetition maximum