One Rep Max Calculator
Estimate your single-rep maximum from any set you have already done, using six published prediction formulas. Every formula is shown side by side with its own result, the average of the set, a full percentage table and a warm-up ramp.
Average estimated 1RM
115.5kg
- Lowest estimate
- Brzycki · 112.5 kg
- Highest estimate
- Mayhew · 119.0 kg
- Spread across formulas
- 6.5 kg
- Weight x reps lifted
- 434% of est. 1RM
Formula by formula
Bar length is relative to the highest estimate. The average sits in the middle of the six.
Percentage of your estimated 1RM
Training loads derived from the average estimate, with the reps that load typically supports (Epley inverted). Your own set is highlighted.
| % of 1RM | Load (kg) | Typical reps | Training effect | Relative load |
|---|---|---|---|---|
| 100% | 115.5 | 1 | Maximal strength | |
| 95% | 109.5 | 2 | Maximal strength | |
| 90% | 104.0 | 4 | Maximal strength | |
| 85% | 98.0 | 6 | Strength | |
| 80% | 92.0 | 8 | Strength | |
| 75% | 86.5 | 10 | Strength / hypertrophy | |
| 70% | 80.5 | 13 | Strength / hypertrophy | |
| 65% | 75.0 | 17 | Hypertrophy | |
| 60% | 69.0 | 21 | Hypertrophy | |
| 55% | 63.5 | 25 | Muscular endurance | |
| 50% | 57.5 | 30 | Muscular endurance |
Warm-up ramp
Five upward sets ending at 85% — enough volume to prime the movement without eating into your working sets. Rest 60–90 seconds between them.
Loads are rounded to the nearest 0.5 kg; the bar floor keeps the first sets at or above the empty bar weight.
These numbers are an estimate for general information only, not medical or coaching advice. Only a properly spotted attempt measures a true one-rep max — never test a maximal lift alone.
About this tool
Enter any set you completed and the calculator runs it through six published prediction equations — Epley, Brzycki, Lombardi, Lander, Mayhew and O'Conner — then averages them. Each formula also drives the percentage table through its own inverse, so the loads and rep counts stay consistent with the formula that produced them. Everything is computed in your browser; nothing is sent anywhere.
- 100% free — no account needed
- Runs in your browser
- Nothing is uploaded
Frequently asked questions
Is One Rep Max Calculator really free?
Yes. One Rep Max Calculator is completely free on PureBrowser — every feature, with no account, no trial, and no credit card.
Does One Rep Max Calculator upload my data?
No. One Rep Max Calculator runs entirely inside your browser, so anything you type, paste, or open stays on your own device.
Do I need to sign up or install anything?
Neither. There is no account and nothing to download — open the page and One Rep Max Calculator is ready to use on desktop or mobile.
Does One Rep Max Calculator work offline?
Once the page has loaded, yes. All of the processing happens locally in your browser, so it keeps working without a connection.
More health & fitness
BMI Calculator
Calculate your Body Mass Index using metric or imperial units with category breakdown.
Sleep Calculator
Find the best bedtime or wake-up time based on 90-minute sleep cycles. Wake up refreshed with this free sleep cycle calculator.
TDEE Calculator
Calculate your Total Daily Energy Expenditure using the Mifflin-St Jeor formula. Find calorie targets for weight loss, maintenance, or muscle gain.
Ideal Weight Calculator
Calculate your ideal body weight using four clinical formulas: Devine, Robinson, Miller, and Hamwi. Supports metric and imperial units.
Heart Rate Zone Calculator
Find your 5 heart rate training zones based on age or max heart rate. Includes the Karvonen formula with fat burn, aerobic, and VO₂ max zones.
Body Fat Calculator
Estimate body fat percentage using the US Navy circumference method. Enter height, neck, waist, and hip measurements to see your body fat category. Metric and imperial supported.