Calculate your One Rep Max for the bench press, squat, or deadlift to optimize your training program.
Your Last Set
5
*Formulas are inaccurate for sets over 10-12 reps
Estimated 1RM
0
Training Percentages
Calculated using the Epley formula. Remember to always use a spotter when attempting maximum weights.
Last updated: August 2026
Understanding Your One Rep Max (1RM)
Your One Rep Max (1RM) is the maximum amount of weight you can lift for a single repetition of an exercise with proper form. Knowing your 1RM is crucial for strength training, as most structured lifting programs prescribe weights based on percentages of your 1RM (e.g., 3 sets of 5 reps at 80% 1RM). However, testing your true 1RM can be dangerous and taxing on the nervous system.
The Formula, With a Worked Example
This calculator uses the Epley formula: 1RM = Weight × (1 + 0.0333 × Reps). For example, lifting 225 lbs for 5 reps gives 225 × (1 + 0.0333 × 5) = 225 × 1.1665 = 262 lbs estimated 1RM. From there, 80% of that number (a common training percentage) works out to about 210 lbs.
How to Use This Tool
Instead of risking injury with a true 1RM test, enter a weight you can comfortably lift for 2 to 10 repetitions. Our calculator uses the Epley formula, one of the most established methods for estimating 1RM, and also provides your percentages for program planning.
Frequently Asked Questions
The Epley and Brzycki formulas are both widely used and considered reasonably accurate for lower rep ranges. This calculator uses Epley specifically. All formulas become less accurate if you enter a weight you lifted for more than 10-12 repetitions.
You don't need to test a true 1RM frequently. Most strength athletes test every 12 to 16 weeks. In between, you can use an estimated 1RM based on your training lifts.
While you can, 1RM calculations are most accurate for major compound barbell lifts like the squat, bench press, deadlift, and overhead press.
If you lifted a weight for exactly one rep, that number already is your one-rep max — there's nothing to estimate. The formula only projects upward from sets of 2 or more reps.
Use your heaviest working set, not a warm-up. Warm-up reps are typically done with lighter weight and less fatigue, which will make the calculator overestimate your true max.
Not always. Epley, Brzycki, and Lombardi are all common formulas and can produce slightly different estimates, especially at higher rep counts. Treat any 1RM estimate as an approximation, not an exact figure.
Formula accuracy drops sharply beyond about 10-12 reps, since the relationship between reps and true strength becomes less linear at higher endurance-driven rep counts.