Free calculator
One-rep max calculator
Your estimated one-rep max from a set of reps, and the weight at every percentage of it. Worked out in your browser; nothing is sent anywhere.
Work out your one-rep max
Estimated 1RM
—lb
| % of 1RM | Weight | About this many reps |
|---|---|---|
| 100% | — | 1 |
| 95% | — | 2 |
| 90% | — | 3 |
| 85% | — | 5 |
| 80% | — | 8 |
| 75% | — | 10 |
| 70% | — | 13 |
| 65% | — | 16 |
| 60% | — | 20 |
| 55% | — | 25 |
| 50% | — | 30 |
Enter the weight and how many clean reps you did.
How it works
Fullday estimates a one-rep max with the Epley formula, from the weight and the reps of one hard set. The rep counts in the table are the same formula turned round, so the chart agrees with the estimate.
1RM = weight × (1 + reps ÷ 30), or the weight itself for a single rep
Reps at a share of 1RM = 30 × (1 ÷ share − 1)
Estimates are closest from sets of 10 reps or fewer: in one study, a 5-rep max predicted the one-rep max better than a 10- or 20-rep max did. It's a guide for choosing training weights, not a test, and real numbers vary by lift and by person.
- Epley B (1985). Poundage Chart. Boyd Epley Workout. Lincoln, NE: Body Enterprises.
- Reynolds JM, Gordon TJ, Robergs RA (2006). Prediction of one repetition maximum strength from multiple repetition maximum testing and anthropometry. Journal of Strength and Conditioning Research, 20(3), 584–592. doi.org/10.1519/R-15304.1
- American College of Sports Medicine (2009). Progression models in resistance training for healthy adults (position stand). Medicine & Science in Sports & Exercise, 41(3), 687–708. pubmed.ncbi.nlm.nih.gov
Questions
How do I calculate my one-rep max?
Multiply the weight by 1 + reps ÷ 30 (the Epley formula). 100 kg for 5 reps gives an estimated one-rep max of about 117 kg; 225 lb for 5 gives about 263 lb.
What if I only did one rep?
Then that weight is your one-rep max, and the calculator shows it as it is. The Epley formula is only used for sets of two reps or more; it's most accurate at 10 reps or fewer.
Should I test my real one-rep max?
You don't need to. An estimate from a hard set of 3–10 reps is close enough to plan training, without the risk of a true maximum lift. If you do test one, warm up well and use a spotter or safety bars.
What percentage of my 1RM should I train at?
It depends on the goal. The American College of Sports Medicine's resistance-training guidance uses heavier loads for fewer reps when building strength, and moderate loads for more reps when building muscle. The table shows roughly how many reps each percentage allows.
Fullday tracks this for you every day.
It estimates each lift's one-rep max with this same formula from your best set every session, and charts it in Progress. Coming to the App Store this December, free to download.
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