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One-rep max calculator
Your one-rep max (1RM) is the most you can lift once with good form. To estimate it without testing, multiply the weight by 1 + reps ÷ 30 (the Epley formula). 100 kg for 5 reps gives an estimated max of about 117 kg. Estimates are most accurate from sets of 2 to 10 reps.
How the calculator works
It uses the Epley formula, the same one Lift Proven uses to track your strength from every set you log:
Estimated 1RM = weight × (1 + reps ÷ 30)
It also shows the Brzycki estimate (weight × 36 ÷ (37 − reps)) as a second opinion. The two agree closely between 3 and 8 reps and drift apart outside that range. Sets above 12 reps are counted as 12, because the more reps you do, the more the result depends on fitness and pain tolerance rather than strength.
Which set should I use?
- A hard set of 3 to 6 reps gives the most reliable estimate. Use your heaviest recent set that you finished with good form.
- Count only clean reps. A rep that needed a spotter or lost depth doesn't count.
- Use a fresh set. Your first work set of the day estimates better than a set done after lots of fatigue.
Using your max to set training weights
Most programmes prescribe weights as a percentage of your max. The table under the calculator shows what you should be able to lift for each rep count, all the way to failure. For normal training you'd stop a rep or two short of that, so take off roughly 2.5 to 5% per rep you want to keep in reserve.
Programmes like 5/3/1 go further and work from a "training max" of 90% of your estimated max, so the weights stay achievable for weeks at a time.
Should I test my true max?
You don't need to. Estimating from a hard set is safer, quicker to recover from and accurate enough to plan training. If you compete or want a verified number, test after a lighter week, with a spotter or safety bars, and work up in small jumps.
Let Lift Proven track your max for you
Log your sets and Lift Proven updates your estimated max on every lift, then sets the weights for your next session from it. No maths, no testing days.
Questions
- What is a one-rep max?
- Your one-rep max (1RM) is the heaviest weight you can lift for a single rep with good form. It is the standard way to measure strength and to set training weights as percentages.
- How accurate is a 1RM calculator?
- From a hard set of 2 to 10 reps, formulas like Epley and Brzycki are usually within a few per cent of a tested max. Accuracy drops with sets over 12 reps.
- Which formula is best, Epley or Brzycki?
- Neither is clearly better. They give almost the same answer between 3 and 8 reps. Epley reads slightly higher for sets above 10 reps. Lift Proven uses Epley.
- How do I estimate my 1RM without testing?
- Do a hard set of 3 to 6 reps with good form, then enter the weight and reps into the calculator. Multiply the weight by 1 + reps ÷ 30 for the Epley estimate.
- What percentage of my 1RM should I train at?
- For strength, most work sits between 75 and 90% of your max for 3 to 6 reps. For muscle, 60 to 80% for 6 to 15 reps taken close to failure works well.