One Rep Max Calculator (1RM)
1RM from weight and reps, with rep and percentage tables
Runs in your browser · nothing is uploaded
Updated 2026-10-04The starting values (100 for 5 reps) are an example. Replace them with the weight and reps you actually did.
Unit
1 to 1,000, including the bar and plates.
1 to 20. Use a set taken close to failure. Estimates are more accurate at 10 reps or fewer.
Estimated 1RM 115.5 kg
Result
- Estimated 1RM (average of 3)
- 115.5 kg
- Epley
- 116.7 kg
- Brzycki
- 112.5 kg
- Lombardi
- 117.5 kg
Weight by rep count
| Reps | % of 1RM | Weight |
|---|---|---|
| 1 | 100% | 115.5 kg |
| 2 | 94.8% | 109.5 kg |
| 3 | 91.6% | 105.9 kg |
| 4 | 89% | 102.8 kg |
| 5 | 86.6% | 100 kg |
| 6 | 84.3% | 97.5 kg |
| 7 | 82.2% | 95 kg |
| 8 | 80.2% | 92.7 kg |
| 9 | 78.3% | 90.5 kg |
| 10 | 76.5% | 88.4 kg |
| 11 | 74.7% | 86.3 kg |
| 12 | 73% | 84.3 kg |
Percentages come from solving each formula backwards and averaging. Use them to pick a weight for, say, a set of 8.
Weight by percentage of 1RM
| % of 1RM | Weight |
|---|---|
| 100% | 115.5 kg |
| 95% | 109.8 kg |
| 90% | 104 kg |
| 85% | 98.2 kg |
| 80% | 92.4 kg |
| 75% | 86.7 kg |
| 70% | 80.9 kg |
| 65% | 75.1 kg |
| 60% | 69.3 kg |
| 55% | 63.5 kg |
| 50% | 57.8 kg |
The math with your numbers
- Epley = 100 × (1 + 5 / 30) = 116.7
- Brzycki = 100 × 36 / (37 − 5) = 112.5
- Lombardi = 100 × 5^0.10 = 117.5
- Average = (116.7 + 112.5 + 117.5) / 3 = 115.5
This is an estimate. Test a true 1RM only after a full warm-up and with a spotter. If you are new to lifting or have an injury or medical condition, skip maximal attempts.
Formulas: Epley B., Poundage Chart (Boyd Epley Workout, 1985); Brzycki M., “Strength testing: predicting a one-rep max from reps-to-fatigue” (JOPERD 1993;64(1):88-90); Lombardi V.P., Beginning Weight Training (1989). The coefficients are the widely quoted ones.
What it is
The one rep max calculator estimates the most you could lift once, using only a weight you lifted for several reps. Testing a true max carries injury risk, so lifters often estimate it from a heavier set of a few reps instead. The calculator shows three well-known formulas and their average, then builds a table of weights for 1 to 12 reps and a table from 50 to 100% of your estimated max, which makes it easy to plan your next session. It opens with an example of 100 for 5 reps.
How to use
- Choose kg or lb.
- Enter the weight lifted, including the bar.
- Enter how many reps you completed with it, close to failure.
- Read the estimated 1RM (average) and each formula’s value.
- Use the tables to find a weight for a target rep count or percentage.
How it works
- Epley: weight × (1 + reps / 30).
- Brzycki: weight × 36 / (37 − reps).
- Lombardi: weight × reps^0.10.
- One rep means the weight is already your max, so all three show the weight itself. Applied literally, Epley would add 3.3% even for one rep.
- The headline value is the average of the three.
- The rep table averages each formula solved backwards (Epley 1 / (1 + r / 30), Brzycki (37 − r) / 36, Lombardi r^−0.1) and multiplies the average 1RM by that percentage.
- Reps must be a whole number from 1 to 20 and weight 1 to 1,000. Values are rounded to 0.1.
Examples
| Set | Epley | Brzycki | Lombardi | Average |
|---|---|---|---|---|
| 100 × 5 | 116.7 | 112.5 | 117.5 | 115.5 |
| 60 × 10 | 80.0 | 80.0 | 75.5 | 78.5 |
| 80 × 8 | 101.3 | 99.3 | 98.5 | 99.7 |
| 140 × 1 | 140 | 140 | 140 | 140 |
Good to know
The formulas describe average trends, so the exercise, your muscle make-up and experience can all move your real max. Warm up properly and use a spotter for any true max attempt. Pair this with the macro calculator to plan your diet, or the heart rate zone calculator for conditioning work.
FAQ
What is a one-rep max?
The heaviest weight you can lift for a single repetition. It is a common reference for setting training loads on lifts such as the squat, bench press and deadlift.
Which formula is most accurate?
It varies by person and lift, so the calculator shows Epley, Brzycki and Lombardi side by side and uses their average as the headline figure. The spread between them gets smaller at low reps (100 × 5 still gives 112.5 to 117.5, about 4% apart).
Can I use a high-rep set?
You can enter 1 to 20 reps, but above 10 the formulas drift apart and may miss your true 1RM by a lot. Use a set of 10 reps or fewer taken close to failure if you can.
How do I pick a weight for 8 reps?
Look at the 8-rep row of the weight-by-reps table. It uses the average of the three formulas solved backwards, so treat it as a starting weight.
Does it work in pounds?
Yes. Switch the unit to lb and everything is shown in pounds. The formulas are the same in either unit.
Related tools
Heart Rate Zone Calculator
Five heart rate zones by % of max and Karvonen
Calories Burned Calculator
Calories burned from MET values, weight and time
Macro Calculator
Split a calorie target into grams of carbs, protein and fat
Body Fat Calculator
Body fat percentage from the US Navy tape method or a BMI estimate