| %1RM | 95% | 90% | 85% | 80% | 75% | 70% |
|---|---|---|---|---|---|---|
| LOAD |
Estimated from your rep work — don't test a true single without a spotter and a reason.
How this 1RM calculator works
Your one-rep max is the heaviest weight you could lift for a single clean rep. You don't need to actually test it — a hard set of 2–10 reps predicts it well. This calculator averages the two most widely used estimation formulas:
Epley: 1RM = w × (1 + r/30) and Brzycki: 1RM = w × 36 / (37 − r)
Epley tends to run slightly high at moderate reps and Brzycki slightly low, so the average lands closer to what most lifters actually pull. Estimates are most accurate at 10 reps or fewer — past that, muscular endurance skews the math, which is why this tool caps input at 12.
How to use the percentages
Programs prescribe working weights as a percentage of 1RM. As a rule of thumb: 85–95% builds maximal strength in the 2–5 rep range, 70–80% is the hypertrophy engine for sets of 6–12, and 65–75% suits volume and technique work. The table above rounds each load to real plate jumps so you can walk it straight to the bar.
FAQ
How accurate are 1RM formulas?
Within roughly 5% for most lifters when the input set is 10 reps or fewer and taken close to failure. Accuracy is best on compound barbell lifts (squat, bench, deadlift) and looser on isolation work.
Should I actually test my one-rep max?
Most people never need to. Estimated 1RM is safer and plenty accurate for programming. If you do test, do it fresh, with a spotter or safeties, after a real warm-up progression.
What set should I enter for the best estimate?
A recent hard set of 3–6 reps taken within a rep or two of failure gives the tightest estimate. A 20-rep grinder will overestimate your max.
How often should my 1RM go up?
Beginners can see monthly jumps; past that, strength moves in blocks. Re-estimate every 4–6 weeks off your top working sets rather than maxing out.