The Epley formula: calculate 1RM from weight and reps
The Epley formula multiplies the weight you lifted by (1 + reps / 30). For 80 kg lifted 8 times, the calculation is 80 × (1 + 8 / 30) = 101.3 kg after rounding. Enter the repetitions you actually completed, not the number planned for the set.
According to Boyd Epley (1985), estimated 1RM = weight × (1 + reps / 30). This page uses that equation, matching Setlane. Wikipedia’s one-repetition maximum article documents the same formula. Public values in the app are rounded to one decimal place; the calculator does the same. There is no repetition cap.
e1RM = weight × (1 + reps / 30)
A worked 92.5 kg × 8 example, plus the bibliographic sources, is in the e1RM guide.
Epley coefficients by repetition count
| Reps | Multiply the lifted weight by |
|---|---|
| 1 | 1.0333 |
| 2 | 1.0667 |
| 3 | 1.1000 |
| 4 | 1.1333 |
| 5 | 1.1667 |
| 6 | 1.2000 |
| 7 | 1.2333 |
| 8 | 1.2667 |
| 9 | 1.3000 |
| 10 | 1.3333 |
These are Epley multipliers, not percentages of your 1RM or a training prescription. Values are displayed to four decimal places; the calculator uses the unrounded formula. It estimates from completed reps without adjusting for RPE or reps in reserve. At one rep it returns 1.0333 times the weight, not the exact value of a tested single.
One-rep max calculation examples
| Weight | Reps | Estimated 1RM |
|---|---|---|
| 80 kg | 8 | 101.3 kg |
| 85 kg | 5 | 99.2 kg |
| 92.5 kg | 8 | 117.2 kg |
| 100 kg | 5 | 116.7 kg |
| 100 lb | 5 | 116.7 lb |
Switching kg/lb changes the unit label; it does not convert the number entered. Use the weight in your chosen unit. With zero weight the result is zero. With one rep, the unchanged Epley equation returns 1.033 times the weight; a tested 100 kg single is still a tested 100 kg single.
Calculate your deadlift 1RM
If you complete 5 deadlift reps with 120 kg, enter 120 in Weight and 5 in Reps. Epley estimates 120 × (1 + 5 / 30) = 140.0 kg estimated 1RM.
Calculate your squat 1RM
A squat set of 100 kg × 5 gives 100 × (1 + 5 / 30) = 116.7 kg estimated 1RM. Enter the repetitions you completed, not the target for the set.
Calculate your bench press 1RM
With 80 kg × 8 on the bench press, the calculation is 80 × (1 + 8 / 30) = 101.3 kg estimated 1RM. You can use the same calculator for all three exercises; there is no need to select one.
In these examples, the weight includes the bar and all plates. These are illustrative calculations, not recommended loads to attempt. Compare your estimates within the same exercise, using the same variation and a comparable range of motion.
How accurate is an estimated one-rep max?
Accuracy depends on the exercise, rep range and how close the set was to your limit. The equation does not know effort, rest time or range of motion. Reynolds, Gordon and Robergs (2006) found 5RM data predicted bench and leg-press 1RM more accurately than 10RM or 20RM data in their study. That does not give every Epley estimate a fixed error margin.
The high-rep reminder on this page appears above 10 reps as a practical caution, not a boundary between accurate and inaccurate results. The calculation is still the same. Read the e1RM guide and worked trend for more context.
The calculator does not write to your account. To follow the sets over time, log them in Setlane and compare progress across completed workouts.
Frequently asked questions
What formula does this one-rep max calculator use?
Epley: estimated 1RM = weight × (1 + reps / 30). The result is rounded to one decimal place, matching Setlane. Enter a non-negative weight and a positive whole number of reps. The same equation is applied at one rep; there is no repetition cap.
Does the kg/lb switch convert my weight?
No. It changes the unit label. Enter the weight in the unit you choose; the estimated result uses that same unit.
Does this calculator save my workout or require an account?
No. It calculates an estimate in your browser. It does not save a workout to Setlane and does not require a login.
