Free tool · 1RM calculator
One-rep max calculator.
No max-out day needed.
Enter the weight and reps of a hard set you did recently. You get an estimate of your one-rep max, and the weight to load for every percentage, so you can program the next weeks without testing a true max.
Estimated one-rep max
260lb
Epley 262.5 · Brzycki 253.1 · Lombardi 264.3
| % | Load | Reps | For |
|---|---|---|---|
| 100% | 260 lb | 1 | Heavy singles to triples |
| 95% | 245 lb | 2 | Heavy singles to triples |
| 90% | 235 lb | 3 | Heavy singles to triples |
| 85% | 220 lb | 5 | Strength |
| 80% | 210 lb | 8 | Strength |
| 75% | 195 lb | 10 | Muscle |
| 70% | 180 lb | 13 | Muscle |
| 65% | 170 lb | 16 | Muscle |
| 60% | 155 lb | 20 | Technique, warm-up |
| 55% | 145 lb | 25 | Technique, warm-up |
| 50% | 130 lb | 30 | Technique, warm-up |
How the estimate works.
A one-rep max (1RM) is the heaviest weight you can lift once with good form. Testing it is tiring and carries some risk, so coaches usually estimate it from a heavier set of a few reps. The calculator averages three classic formulas: Epley (weight × (1 + reps ÷ 30)), Brzycki (weight × 36 ÷ (37 − reps)) and Lombardi (weight × reps^0.10).
They agree closely for sets of two to ten reps and drift apart beyond, so the calculator stops at twelve. The estimate is best when the set was close to failure: if you stopped with three reps left, your real max is higher than shown.
Using the percentage chart.
The chart turns your max into training weights, rounded to 2.5 kg or 5 lb. As a rule of thumb, 90–100% is for singles, doubles and triples, 80–85% builds strength in sets of 3 to 6, 65–75% suits hypertrophy work in sets of 8 to 12, and lighter weights are for technique, warm-ups and endurance.
The rep counts are averages: they vary between lifts and between people. Squats often allow more reps at a given percentage than the bench press, and a well-trained lifter can do fewer reps at 85% than a beginner. Use them as a starting point, then adjust to how the bar moves.
Tips for an accurate number.
Use a set from the last two weeks, done with full range of motion. Lower-rep sets give a closer estimate: a set of 3 to 5 beats a set of 12. Calculate each lift separately, and recalculate after each training block.
- Warm up as for a heavy session before the set you use
- Count only reps with good form
- Stop the set if your form breaks down: the estimate is still useful
In the app
Let Lifterly keep the numbers.
Lifterly records every set and keeps your heaviest lift and best session on each exercise. With Pro, the planner sets your next targets from what you lifted last time, and your strength score shows where each muscle stands.
Questions
A few things worth knowing.
How accurate is a one-rep max calculator?
Within a few percent for most people, when the set is heavy (2 to 6 reps) and close to failure. Accuracy drops with high-rep sets and with very strong or very new lifters, which is why the calculator stops at 12 reps.
Which 1RM formula is the best?
None wins everywhere. Epley tends to read higher at low reps, Brzycki lower at high reps. Averaging the three, as the calculator does, smooths out their biases.
Should I test my real one-rep max?
Only if you need it, for a competition for example. For programming, an estimate from a hard set is accurate enough, safer and doesn’t cost you a recovery day.
How often should I recalculate my 1RM?
At the end of each training block, usually every 4 to 8 weeks, or whenever your working sets start feeling noticeably lighter.
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