One rep max calculator
Estimate the most weight you can lift for a single rep — from any set you've already done. No max-out day required.
Estimated one rep max
258lb
Epley 263 lb · Brzycki 253 lb
| % of 1RM | Weight | Typical reps |
|---|---|---|
| 100% | 257.5 lb | 1 |
| 95% | 245 lb | 2 |
| 90% | 232.5 lb | 4 |
| 85% | 220 lb | 6 |
| 80% | 207.5 lb | 8 |
| 75% | 192.5 lb | 10 |
| 70% | 180 lb | 12 |
| 65% | 167.5 lb | 15 |
| 60% | 155 lb | 20+ |
How the estimate works
We run your set through the two most-validated estimation formulas and average them. Epley computes weight × (1 + reps ÷ 30); Brzycki computes weight × 36 ÷ (37 − reps). They agree almost exactly at low reps and bracket the truth at higher reps — Epley runs slightly optimistic, Brzycki slightly conservative.
The percentage table is where the number becomes useful: strength programs prescribe sets like "5 reps at 80%", and the table converts each percentage into actual plates on the bar, rounded to the nearest 2.5 so it's loadable.
Frequently asked questions
What is a one rep max?
Your one rep max (1RM) is the most weight you can lift for a single rep with full range of motion and solid form. It's the reference number strength programs are built around — most prescribe working weights as a percentage of it.
How accurate are 1RM calculators?
Within a few percent for sets of 10 reps or fewer, and best under 6. Past 10 reps the estimate drifts because endurance starts doing more of the work than raw strength. Formulas also vary slightly by lift — most people overshoot on deadlift estimates and undershoot on bench.
Should I actually test my 1RM instead?
Usually not. A true max attempt carries injury risk, costs a training day, and needs a spotter. An estimate from a hard set of 3–5 reps gives you a number accurate enough to program from, which is all most lifters need it for.
What percentage of my 1RM should I train at?
It depends on the goal: roughly 80–95% for strength work in the 2–6 rep range, 65–80% for muscle growth in the 8–12 rep range, and 60% or less for technique and speed work. The table above maps each percentage to the reps typically possible there.
More free tools
Strength standards
See whether your squat, bench, deadlift and press are beginner, intermediate or elite for your bodyweight.
Warm-up sets calculator
The exact ramp to your working weight — bar to top set, plate-rounded.
Plate loading calculator
Which plates go on each side of the bar for any target weight.
Coach? The numbers are the easy part.
AirFit turns them into programs, meal plans and booked sessions — with client access on iOS, Android and the web. Free forever for your first 5 clients.
Just here to train? Get your free AirFit Coach program — a program, meal plan and daily protocol built from your numbers, 7-day trial — or find a human coach on AirFit.