This 1RM calculator uses weight and reps1 performed to estimate your one rep max.
The formula used for this calculation is: 1RM = Weight in pounds/(1.0278-(.0278 x reps1))
This table below helps you figure out what weight to use (+/- 5 pounds) for a goal number of reps based on your 1RM. For example, if your 1RM is 250 and you wanted to do a set of 8 reps, multiple 250 by .786 to get 196.5 for a weigh range of 191.5 - 201.5 pounds for your 8 rep set. If you've been doing lighter weight for more reps (10+), or heavier weight for fewer reps (3 or less), it won't be as accurate.
Enter you 1RM and the coefficient based on your rep goal into the form below and click calcualte.
| Reps | CoEfficient |
| 1 | 1.00 |
| 2 | .943 |
| 3 | .906 |
| 4 | .881 |
| 5 | .856 |
| 6 | .831 |
| 7 | .807 |
| 8 | .786 |
| 9 | .765 |
| 10 | .744 |
| Reps | CoEfficient |
| 11 | .723 |
| 12 | .703 |
| 13 | .688 |
| 14 | .675 |
| 15 | .662 |
| 16 | .650 |
| 17 | .638 |
| 18 | .627 |
| 19 | .616 |
| 20 | .606 |
Here's another chart with values you can use to calculate your one rep max based on the exercise and reps.
| Repetitions | Squat | Benchpress | Deadlift |
| 1 | 1.0 | 1.0 | 1.0 |
| 2 | 1.0475 | 1.035 | 1.065 |
| 3 | 1.13 | 1.08 | 1.13 |
| 4 | 1.1575 | 1.115 | 1.147 |
| 5 | 1.2 | 1.15 | 1.164 |
| 6 | 1.242 | 1.18 | 1.181 |
| 7 | 1.284 | 1.22 | 1.198 |
| 8 | 1.326 | 1.255 | 1.232 |
| 9 | 1.368 | 1.29 | 1.232 |
| 10 | 1.41 | 1.325 | 1.24 |
This formual estimates your one rep max based on reps and weight used. Enter reps and the weight into the form beliow click calculate. ((Reps x .033) + 1) x Weight