One-Rep Max Calculator
The weight you lifted, including the bar.
How many clean reps you completed (1–12).
All three estimate within ~10% of your true max. We show every formula so you can compare.
| Epley | – |
| Brzycki | – |
| Lombardi | – |
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How the one-rep max calculator works
Enter the weight you lifted and how many clean reps you managed, and the calculator estimates the heaviest single rep you could do. It uses three validated formulas — Epley, Brzycki and Lombardi — shown side by side so you can see the range instead of one possibly-flattering number.
The training weights table turns your max into a program: percentages of 1RM with the rep ranges coaches actually use for strength, hypertrophy and endurance work.
Why lifters use 1RM percentages
Percentages let you train at the right intensity without maxing out every session — which is how progress stalls and injuries happen. Work mostly in the 70–90% zone, test occasionally, and recalculate as your lifts climb.
Frequently asked questions
How accurate is a 1RM estimate?
Within about 10% of your true max when based on 3–10 clean reps. Singles and very high reps are less reliable — the calculator warns you past 12 reps. Nothing beats an actual tested max for programming.
Which formula should I trust?
Epley and Brzycki are the most validated and agree closely up to 10 reps; Lombardi runs a little higher. We show all three so you can see the spread instead of hiding the uncertainty.
How do I use the % table?
Base your working sets on it: ~85–95% for strength (1–5 reps), ~70–85% for muscle growth (6–12 reps), ~60–70% for endurance or warm-ups. Retest or recalculate every 4–8 weeks as you get stronger.
Should I attempt a true 1RM?
Only with experience, a spotter, and a good warm-up — and never when fatigued or injured. For most lifters, the estimate plus the % table is safer and just as useful.