Free lifting calculator
One Rep Max Calculator with RPE
Enter a weight, your reps and how hard the set felt to estimate your 1RM, see your 1 to 10 rep-max table, and find the working weight for any reps at any RPE. For bench press, squat and deadlift, see where your max sits among members.
- Uses the Wathan formula, the same one behind your Strength Score
- Optional RPE adjusts the estimate for the reps you had left
- Working weight mode: enter your max, target reps and RPE to get the load
- Accepts kilograms or pounds without changing the underlying estimate
- Percentage chart from 1 to 30 reps, with weights for a 100 kg and a 225 lb max
- Bench press, squat and deadlift: your estimate placed among members who log the lift
- Free to use, no account needed
How this calculator works
The calculator uses the Wathan equation. Enter the weight from one completed set and a whole-number repetition count from 1 to 20. Add an RPE if you stopped short of failure. The calculator estimates the equivalent one-rep max, then works back from that estimate to build the 1 to 10 rep-max table. Pounds and kilograms use the same equation, and the result stays in the unit you entered.
How RPE changes the estimate
RPE rates how hard a set was on a 10-point scale counted in reps you had left: RPE 10 means none, RPE 9 means one, RPE 8 means two. Mike Tuchscherer brought this kind of scale to powerlifting in The Reactive Training Manual. Zourdos and colleagues tied each RPE to reps in reserve, and Helms and colleagues described its use in 2016. The calculator adds the reps you had left to the reps you did, so 5 reps at RPE 8 counts as a 7-rep max, then runs that through the Wathan equation. A half step such as 8.5 sits halfway between 8 and 9. The published scale rates 5 to 6 as 4 to 6 reps left; this calculator reads RPE 6 as 4 left, the same scale the set logger uses.
Find a working weight
Switch to Working weight and enter your max, the reps you plan and the RPE you want to finish at. The calculator runs the same chart in reverse: 5 reps at RPE 8 from a 300 lb max is 80.6% of that max, 241.9 lb, so load 240 lb. The result also lists the same reps at every other RPE.
Choose an input set you can trust
Use a recent set performed with the same exercise, range of motion, equipment, and technique you plan to compare later. A set stopped far from your actual limit can understate the estimate, while a set with shortened range of motion or inconsistent assistance can overstate it. Sets of 1 to 10 reps give the steadiest estimate. Sets of 11 to 20 are accepted here with a warning, because fatigue and pacing make longer sets less reliable, and an RPE guess is least accurate on a set that ends far from failure.
Use the estimate for training decisions
Treat the result as a loading reference, not a challenge to test immediately. It can help you choose percentage-based working weights, compare equivalent performances across rep ranges, and track whether the same lift is improving over time. Compare like with like: a paused bench press, touch-and-go bench press, machine press, and dumbbell press do not share one interchangeable maximum.
What the number does not prove
The estimate does not guarantee that you can complete a true one-rep attempt on a given day. Exercise skill, fatigue, rest, repetition speed, equipment, and individual endurance all affect the relationship between a multi-rep set and a maximum single. Use a qualified coach or experienced spotters when a real maximal attempt is appropriate.
Bench press one-rep max
A bench press of 225 lb for 5 reps gives an estimated 262.3 lb one-rep max with the Wathan formula. In kilograms, 100 kg for 5 reps gives 116.6 kg. Among Symmetric Strength members who log the bench press, the median estimated one-rep max is 207 lb (94 kg) for men (29,107 lifters) and 103 lb (47 kg) for women (2,929 lifters), as of October 18, 2026. These are members' logged lifts, not a population average. Pick this lift under Compare with members in the calculator to see where your own estimate sits.
Squat one-rep max
A squat of 315 lb for 5 reps gives an estimated 367.2 lb one-rep max with the Wathan formula. In kilograms, 140 kg for 5 reps gives 163.2 kg. Among Symmetric Strength members who log the squat, the median estimated one-rep max is 271 lb (123 kg) for men (28,410 lifters) and 167 lb (76 kg) for women (2,996 lifters), as of October 18, 2026. These are members' logged lifts, not a population average. Pick this lift under Compare with members in the calculator to see where your own estimate sits.
Deadlift one-rep max
A deadlift of 405 lb for 3 reps gives an estimated 441.4 lb one-rep max with the Wathan formula. In kilograms, 180 kg for 3 reps gives 196.2 kg. Among Symmetric Strength members who log the conventional deadlift, the median estimated one-rep max is 325 lb (147 kg) for men (27,449 lifters) and 200 lb (91 kg) for women (2,815 lifters), as of October 18, 2026. These are members' logged lifts, not a population average. Pick this lift under Compare with members in the calculator to see where your own estimate sits.
Do I need to test a true one-rep max?
No. A recent set of 1 to 10 reps is enough for a solid estimate, and a set of up to 20 reps or a set rated by RPE gives a rougher one. For routine programming, repeating the same controlled test set is often more useful than frequently attempting a maximum single.
Should I enter pounds or kilograms?
Use the unit shown on your training record or plates. The calculator applies the same equation and returns the estimate in that same unit.
Why can two calculators give different answers?
Rep-max equations model the relationship between weight and repetitions differently. For 100 kg lifted for 5 reps, Wathan gives 116.6 kg, Epley 116.7 kg and Brzycki 112.5 kg. With RPE left blank and 1 to 10 reps, this calculator and your Strength Score use the same Wathan equation on the same set.
What does RPE 8 mean?
You finished the set with about two good reps left. RPE 10 is a set you could not have added a rep to, RPE 9 leaves one rep and RPE 7 leaves three. This calculator places a half step such as 8.5 halfway between 8 and 9.
How accurate is an RPE chart?
It shows an average, and individual lifters differ from it. For the reps and RPEs Helms and colleagues published in 2016, this chart stays within a few percentage points of theirs. Their paper warns that such a table is not an absolute conversion tool because people differ, and that beginners and sets far from failure give the least accurate ratings.
Methodology reviewed .
Percentage of your one-rep max by reps
| Reps | % of 1RM | With a 100 kg max | With a 225 lb max |
|---|---|---|---|
| 1 | 100% | 100 kg | 225 lb |
| 2 | 95.1% | 95 kg | 215 lb |
| 3 | 91.8% | 92 kg | 207.5 lb |
| 4 | 88.7% | 88.5 kg | 200 lb |
| 5 | 85.8% | 86 kg | 192.5 lb |
| 6 | 83.1% | 83 kg | 187.5 lb |
| 7 | 80.6% | 80.5 kg | 182.5 lb |
| 8 | 78.3% | 78.5 kg | 175 lb |
| 9 | 76.2% | 76 kg | 172.5 lb |
| 10 | 74.2% | 74 kg | 167.5 lb |
| 11 | 72.4% | 72.5 kg | 162.5 lb |
| 12 | 70.7% | 70.5 kg | 160 lb |
| 13 | 69.1% | 69 kg | 155 lb |
| 14 | 67.6% | 67.5 kg | 152.5 lb |
| 15 | 66.3% | 66.5 kg | 150 lb |
| 16 | 65.0% | 65 kg | 147.5 lb |
| 17 | 63.8% | 64 kg | 142.5 lb |
| 18 | 62.7% | 62.5 kg | 140 lb |
| 19 | 61.7% | 61.5 kg | 140 lb |
| 20 | 60.8% | 61 kg | 137.5 lb |
| 21 | 59.9% | 60 kg | 135 lb |
| 22 | 59.1% | 59 kg | 132.5 lb |
| 23 | 58.4% | 58.5 kg | 132.5 lb |
| 24 | 57.7% | 57.5 kg | 130 lb |
| 25 | 57.1% | 57 kg | 127.5 lb |
| 26 | 56.5% | 56.5 kg | 127.5 lb |
| 27 | 55.9% | 56 kg | 125 lb |
| 28 | 55.4% | 55.5 kg | 125 lb |
| 29 | 54.9% | 55 kg | 122.5 lb |
| 30 | 54.5% | 54.5 kg | 122.5 lb |
Wathan formula, the same one this calculator uses. Percentages are rounded to 0.1%, weights to the nearest 0.5 kg and 2.5 lb. Rows 1 to 10 are the most reliable. Past 10 reps the numbers get rougher, and rows 21 to 30 extend the curve beyond the 20 reps the calculator accepts as input. Treat every row as a starting point: fatigue, rest and technique move the real numbers.
RPE chart: percent of your one-rep max
| Reps | RPE 10 | RPE 9.5 | RPE 9 | RPE 8.5 | RPE 8 | RPE 7.5 | RPE 7 | RPE 6.5 | RPE 6 |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 100% | 97.6% | 95.1% | 93.4% | 91.8% | 90.2% | 88.7% | 87.2% | 85.8% |
| 2 | 95.1% | 93.4% | 91.8% | 90.2% | 88.7% | 87.2% | 85.8% | 84.4% | 83.1% |
| 3 | 91.8% | 90.2% | 88.7% | 87.2% | 85.8% | 84.4% | 83.1% | 81.9% | 80.6% |
| 4 | 88.7% | 87.2% | 85.8% | 84.4% | 83.1% | 81.9% | 80.6% | 79.5% | 78.3% |
| 5 | 85.8% | 84.4% | 83.1% | 81.9% | 80.6% | 79.5% | 78.3% | 77.3% | 76.2% |
| 6 | 83.1% | 81.9% | 80.6% | 79.5% | 78.3% | 77.3% | 76.2% | 75.2% | 74.2% |
| 7 | 80.6% | 79.5% | 78.3% | 77.3% | 76.2% | 75.2% | 74.2% | 73.3% | 72.4% |
| 8 | 78.3% | 77.3% | 76.2% | 75.2% | 74.2% | 73.3% | 72.4% | 71.5% | 70.7% |
| 9 | 76.2% | 75.2% | 74.2% | 73.3% | 72.4% | 71.5% | 70.7% | 69.9% | 69.1% |
| 10 | 74.2% | 73.3% | 72.4% | 71.5% | 70.7% | 69.9% | 69.1% | 68.4% | 67.6% |
| 11 | 72.4% | 71.5% | 70.7% | 69.9% | 69.1% | 68.4% | 67.6% | 66.9% | 66.3% |
| 12 | 70.7% | 69.9% | 69.1% | 68.4% | 67.6% | 66.9% | 66.3% | 65.6% | 65.0% |
Each cell is the Wathan percentage for the reps you did plus the reps you had left. Divide a set's weight by its cell to estimate your max, or multiply your max by a cell to find a working weight. Helms and colleagues published data for 1 to 8 reps at RPE 7 to 10. Every other cell extends the same curve past their data and is rougher.