One-rep max calculator
Put in a weight and the reps you got with it. Five published formulas estimate your one-rep max, side by side, so you can see how much they disagree — because they do, and pretending otherwise is how people pick a number that gets them hurt.
Estimate a max from a set
Why five formulas and not one
Every one of these was fitted to a different group of lifters doing a different lift, and none of them was fitted to you. They agree closely at three reps and spread out badly past eight, which is the single most useful thing to know about them.
| Formula | The math | Where it drifts |
|---|---|---|
| Epley | w × (1 + r ÷ 30) | Runs high on long sets. The most quoted of the five. |
| Brzycki | w ÷ (1.0278 − 0.0278r) | Runs low above ten reps, and breaks down entirely near 37. |
| Lander | 100w ÷ (101.3 − 2.67123r) | Close to Brzycki through the middle of the range. |
| Lombardi | w × r0.10 | The most conservative on long sets. |
| Mayhew | 100w ÷ (52.2 + 41.9 × e−0.055r) | Fitted on bench press; treat squat and deadlift output with more suspicion. |
How to use the number without getting hurt
- Use a set of two to five. Every formula is at its most accurate close to a real max. A set of twelve is a test of conditioning as much as strength, and the estimate you get from it can be off by more than the plates you would add.
- Take the low end, not the average. If the five numbers span 300 to 320, program off 300. Being 20 lb conservative costs you one session. Being 20 lb optimistic under a bar costs you more than that.
- The set has to have been honest. An estimate from a set you grinded to failure with a spotter touching the bar is not an estimate of anything.
- Re-estimate every few weeks, not every session. The number moves slower than your motivation to check it.
Percentages off your max
Most programs are written as percentages. Once you have a working max, this is the table you actually use week to week:
| Percent of max | Reps usually available | What it is for |
|---|---|---|
| 95–100% | 1 | Testing, or a heavy single |
| 90% | 2–3 | Peaking work |
| 85% | 4–5 | The main strength range |
| 80% | 6–7 | Volume that still moves strength |
| 75% | 8–10 | Hypertrophy, technique work |
| 65–70% | 12–15 | Back-off sets, deloads |
Reps-at-percentage is an average across lifters and lifts, not a rule. Squat tends to give up more reps at a given percentage than deadlift does.
Where this fits in a training week
An estimated max is only useful if something downstream uses it. In EatSleepRep the workout log keeps every set you have logged, so your best recent effort at each rep count is already recorded and you are not estimating from memory. Log the set, and the plate math for the next one is right there.
Strength is also downstream of the other two jobs. If the estimate has not moved in two months, the protein calculator and a look at your sleep will usually explain more than a new program will. What to eat to hit the number is in the food macros reference, built on USDA records rather than crowd-sourced entries.
Coaches estimating maxes for a whole roster have a different problem, which is software rather than arithmetic. The for-coaches guides compare what the team platforms publish and what they charge.
Open it and close today
No signup to try it. Log a meal, log last night, log a set — the ring closes and the chain starts.
Common questions
Most accurate from a set of two to five reps, where the formulas agree closely. Past eight reps they spread out badly and the honest reading is a range rather than a number.
None of them is best for everyone. Epley runs high on long sets, Lombardi runs conservative, and Mayhew was fitted on bench press. Seeing all five together tells you how much uncertainty you are actually working with. Program off the low end.
Re-estimate every few weeks rather than every session. A true max test is taxing and the number moves slower than the urge to check it.
Roughly 85 percent for sets of four to five is the main strength range, 75 percent for sets of eight to ten builds size, and 65 to 70 percent is back-off and deload work. Those are averages across lifters and lifts, not rules.