One-rep-max
One-Rep-Max Calculator
Estimate your 1RM from any set without testing a true max. Enter the weight and reps, see the Epley and Brzycki estimates, and read every training percentage off the table.
Most accurate at 1–10 reps. Beyond ~12, estimates drift.
Epley
116.7 kg
Brzycki
112.5 kg
| % 1RM | Load | Reps |
|---|---|---|
| 100% | 114.6 kg | 1 |
| 95% | 108.9 kg | 2 |
| 90% | 103.1 kg | 3–4 |
| 85% | 97.4 kg | 5–6 |
| 80% | 91.7 kg | 7–8 |
| 75% | 86 kg | 9–10 |
| 70% | 80.2 kg | 11–12 |
| 65% | 74.5 kg | 13–15 |
| 60% | 68.8 kg | 16–20 |
Use these loads to program your working sets — strength work sits at 85%+, hypertrophy around 65–80%.
Estimates only. Lift within your ability, warm up thoroughly, and use a spotter for heavy attempts. This is not coaching or medical advice.
How to estimate and use your 1RM
Your one-rep max is the cleanest single measure of how strong you are on a given lift, but you rarely need to actually grind out a true single to know it. Strength researchers long ago worked out that the weight you can move for a handful of reps predicts your max with useful accuracy — the more reps, the more the estimate leans on conditioning rather than pure strength, which is why a heavy set of three to six is the sweet spot.
This calculator runs two of the most-cited formulas. The Epley equation, 1RM = w × (1 + reps ÷ 30), and the Brzycki equation, 1RM = w × 36 ÷ (37 − reps). They agree almost exactly at low reps and diverge slightly as reps rise, so we feature the average of the two as your headline number and show both so you can see the spread.
The percentage table is where the estimate earns its keep. Almost every structured program prescribes load as a percentage of 1RM: a strength block might call for sets at 87.5%, a hypertrophy block for 70–75%, a deload for 60%. Rather than doing the math each session, read the load straight off the table for the percentage your program asks for. As you get stronger, re-enter a fresh heavy set every few weeks to keep the numbers — and your working weights — honest.
FAQ
Frequently asked questions
- What is a one-rep max?
- Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition of an exercise with good form. It's the standard benchmark of maximal strength and the reference point most programs use to assign training loads.
- How is 1RM calculated from reps?
- This calculator uses two well-known formulas. Epley: 1RM = weight × (1 + reps ÷ 30). Brzycki: 1RM = weight × 36 ÷ (37 − reps). We show both and feature their average, since neither is perfect and they bracket a realistic estimate.
- How accurate is an estimated 1RM?
- Very accurate at low reps and increasingly approximate as reps climb. A set of 2–5 reps gives a tight estimate; a set of 12+ reps depends heavily on conditioning and technique, so the prediction can be off by several percent. For the best estimate, use a heavy set you took close to failure.
- How do I use the percentage table?
- Programs prescribe loads as a percentage of your 1RM. Maximal-strength work usually sits at 85% and above for low reps; hypertrophy work lives around 65–80% for moderate reps. Read the load straight off the table and use it to set your working weights, then re-test periodically as you get stronger.
- Should I actually attempt a one-rep max?
- You don't need to. Estimating from a heavy set of 3–6 reps is safer, repeatable, and accurate enough for programming. True 1RM testing carries more injury risk and is best reserved for experienced lifters with a spotter and a proper warm-up.
Grind Track
Track this in the app
Grind Track estimates your e1RM automatically from every set you log, charts it over time, and stamps a PR the moment you hit one. Your strength, tracked without the spreadsheet. Free to start on iPhone.