Physique PalFree tool
One rep max calculator
Enter a set you actually completed and get your estimated 1RM from four proven formulas — plus every training percentage worked out for you.
Estimated one-rep max
265 lb
Based on 225 lb × 5 reps using the Epley formula. Unrounded: 262.5 lb.
What the other formulas say
| Formula | Estimated 1RM |
|---|---|
| Epley | 265 lb |
| Brzycki | 255 lb |
| Lombardi | 265 lb |
| O'Conner | 255 lb |
Your training percentages
| % of 1RM | Weight | Typical reps | Used for |
|---|---|---|---|
| 100% | 265 lb | 1 | True max |
| 95% | 250 lb | 2 | Peaking |
| 90% | 235 lb | 3–4 | Heavy strength |
| 85% | 225 lb | 5–6 | Strength |
| 80% | 210 lb | 7–8 | Strength / size |
| 75% | 195 lb | 9–10 | Hypertrophy |
| 70% | 185 lb | 11–12 | Hypertrophy |
| 65% | 170 lb | 13–15 | Volume work |
| 60% | 160 lb | 16–20 | Endurance / technique |
The formulas
How one-rep max is calculated
Every 1RM formula does the same thing: it takes a weight you lifted for multiple reps and extrapolates what you could have managed for one. They differ only in how aggressively they extrapolate.
Epley
1RM = w × (1 + r ÷ 30)The most commonly used, and the default here. A set of 5 at 225 lb estimates to 262.5 lb.
Brzycki
1RM = w × 36 ÷ (37 − r)Agrees with Epley almost exactly at low reps and reads lower as reps climb. Breaks down near 37 reps, where the denominator reaches zero.
Lombardi
1RM = w × r^0.10The most conservative of the four, which makes it a good sanity check when the others look optimistic.
O’Conner
1RM = w × (1 + 0.025 × r)A simple linear model that sits between Brzycki and Lombardi in practice.
Why four instead of one
All four converge at a single rep and fan out from there. Past roughly ten reps they can disagree by 10% or more — and that disagreement is itself the useful signal. It means you did too many reps for a confident estimate, which one confident-looking number would have hidden from you.
Programming
Training percentages of your one-rep max
Most strength programs prescribe load as a percentage of 1RM. These are the conventional reference points — the rep figures are typical ranges rather than guarantees, and where you land in them depends on the lift and how well you tolerate volume.
| % of 1RM | Typical reps | What it’s used for |
|---|---|---|
| 100% | 1 | True max |
| 95% | 2 | Peaking |
| 90% | 3–4 | Heavy strength |
| 85% | 5–6 | Strength |
| 80% | 7–8 | Strength / size |
| 75% | 9–10 | Hypertrophy |
| 70% | 11–12 | Hypertrophy |
| 65% | 13–15 | Volume work |
| 60% | 16–20 | Endurance / technique |
FAQ
One rep max questions
What is a one-rep max?
Your one-rep max, or 1RM, is the heaviest weight you can lift for a single rep with good form. It is the reference number most strength programs are built around — sets are prescribed as a percentage of it rather than as an absolute weight.
How accurate are 1RM calculators?
They are good estimates in the 1–5 rep range and get progressively less reliable as reps climb. Past roughly ten reps the set is limited as much by conditioning as by strength, and the formulas start disagreeing with each other by 10% or more. Use the estimate to pick training weights, not to decide what to attempt on a max day.
Which formula should I use?
Epley is the most widely used and is the default here. Brzycki tends to read slightly lower at higher reps, Lombardi is more conservative across the board, and O'Conner sits between them. If they disagree meaningfully, that disagreement is itself the useful signal — you did too many reps for a confident estimate.
Should I actually test my one-rep max?
Rarely, and not if you are new to a lift. A true max attempt is technically demanding and takes real recovery. Estimating from a hard set of 3–5 gives you a number you can program with at a fraction of the cost.
How do I use the percentage chart?
Find the row matching the goal of the session — around 85–90% for heavy strength work, 70–80% for hypertrophy — and load the weight in that row. The rep figures are typical ranges, not targets you must hit exactly.
Your real numbers beat any formula
Physique Pal logs every set you do, tracks your personal records automatically, and shows you what you lifted last time before you start the set — so your training weights come from your own history instead of an estimate.
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