Epley 1rm Calculator
Track your epley 1rm with our free sports calculator. Get personalized stats, rankings, and performance comparisons. Includes formulas and worked examples.
Formula
1RM = Weight x (1 + Reps / 30)
The Epley formula estimates one-rep max by multiplying the weight lifted by a factor that increases linearly with reps. Each additional rep adds approximately 3.33% to the multiplier, making the estimate progressively higher at higher rep counts.
Worked Examples
Example 1: Bench Press 1RM Estimation
Problem: A lifter bench presses 200 lbs for 6 reps to failure. Calculate the estimated 1RM using the Epley formula.
Solution: Epley Formula: 1RM = Weight x (1 + Reps / 30)\n1RM = 200 x (1 + 6 / 30)\n1RM = 200 x (1 + 0.2)\n1RM = 200 x 1.2\n1RM = 240 lbs\nTraining Max (90%) = 240 x 0.9 = 216 lbs\nThe weight used (200 lbs) represents 83.3% of estimated 1RM
Result: Estimated 1RM: 240 lbs | Training Max: 216 lbs | Weight Used: 83.3% of 1RM
Example 2: Squat Multi-Formula Comparison
Problem: A lifter squats 315 lbs for 4 reps to failure. Compare estimates from five different formulas.
Solution: Epley: 315 x (1 + 4/30) = 315 x 1.133 = 357.0 lbs\nBrzycki: 315 / (1.0278 - 0.0278 x 4) = 315 / 0.9166 = 343.7 lbs\nLander: (100 x 315) / (101.3 - 2.67 x 4) = 31500 / 90.62 = 347.6 lbs\nAverage of 3 = 349.4 lbs\nTraining Max = 349.4 x 0.9 = 314.5 lbs
Result: Epley: 357 lbs | Brzycki: 343.7 lbs | Average: 349.4 lbs
Frequently Asked Questions
What is the Epley formula and who developed it?
The Epley formula is a widely used one-rep max estimation equation developed by Boyd Epley, a pioneering strength coach at the University of Nebraska. The formula is expressed as: 1RM = Weight x (1 + Reps / 30). It estimates the maximum weight an athlete can lift for a single repetition based on the weight used and repetitions completed in a submaximal set. The Epley formula is known for its simplicity and reasonable accuracy, particularly in the 1-10 rep range. It was one of the earliest 1RM prediction equations and has been validated across numerous research studies. Many strength training programs and fitness apps use the Epley formula as their default 1RM calculator due to its straightforward calculation.
How does the Epley formula compare to other 1RM prediction equations?
The Epley formula tends to produce slightly higher estimates than the Brzycki formula at higher rep ranges (8+), while both converge at lower rep ranges (1-5). Compared to the Lander formula, Epley typically gives estimates within 2-3% for sets of 5 reps or fewer. The Wathen and Mayhew formulas use exponential functions and may provide better accuracy at very high rep counts (15+). Research published in the Journal of Strength and Conditioning Research shows no single formula is universally superior across all exercises and populations. The best practice is to compare multiple formulas and use the average, which is why Epley 1rm Calculator displays results from five different equations simultaneously. Each formula has specific populations where it performs best.
What rep range gives the most accurate Epley 1RM estimate?
The Epley formula is most accurate when used with sets of 2-10 repetitions performed to muscular failure. Within this range, estimates typically fall within 3-5% of actual tested 1RM values. Sets of 3-6 reps tend to produce the most precise estimates because they are heavy enough to closely reflect maximal strength capacity while providing enough data points for the formula. At 1-2 reps, the estimate is highly accurate but you are already close to your actual max, making the estimate somewhat redundant. Beyond 10 reps, accuracy degrades significantly because muscular endurance, cardiovascular factors, and mental toughness begin to influence how many reps you complete, introducing noise into the estimation process.
Does the Epley formula work for all types of exercises?
The Epley formula was primarily validated using compound barbell exercises such as bench press, squat, and deadlift, and it performs best with these movements. For isolation exercises like bicep curls, tricep extensions, and leg curls, the formula may overestimate 1RM because these exercises have different fatigue profiles and rely more on single muscle groups. Machine exercises may also produce less reliable estimates due to variable resistance curves and reduced stabilizer muscle involvement. The formula should not be used for Olympic lifts like cleans and snatches, where technical proficiency determines failure rather than muscular exhaustion. For bodyweight exercises, the formula can be adapted by adding external load to your body weight for the calculation.
Can I use the Epley formula if I did not reach true muscular failure?
The Epley formula assumes that the reps entered represent a set taken to complete muscular failure, meaning you could not have performed even one more repetition with proper form. If you stopped a set with reps in reserve (RIR), the formula will underestimate your true 1RM. For example, if you did 200 lbs for 6 reps but had 2 reps left in the tank, you should either add those 2 reps to the input (entering 8 reps) or increase the weight to what you estimate you could have done for the same 6 reps to failure. Some modern training approaches use Rate of Perceived Exertion (RPE) scales to account for this, where RPE 10 equals true failure and RPE 8 means 2 reps in reserve. Accurate 1RM estimation always requires honest assessment of effort level.
Is Epley 1rm Calculator free to use?
Yes, completely free with no sign-up required. All calculators on NovaCalculator are free to use without registration, subscription, or payment.