One Rep Max (1RM) Calculator

Follow these steps to estimate your one rep max and determine training weights:

1. Enter the weight you lifted. Use a weight you have actually lifted for the specified number of reps with good form. This should be a recent lift, not from years ago. Enter the weight in pounds.
2. Enter the number of reps performed. Input the number of repetitions you completed at that weight. The calculator is most accurate for rep ranges of 1 to 10 reps. Estimates become less reliable above 10 reps because the formula assumes a predictable relationship between reps and intensity.
3. Review your estimated 1RM and training weights. The calculator instantly displays your estimated one rep max and the appropriate training weights at different percentages. Your training max is shown at 90 percent of 1RM, which is the conservative weight many strength coaches recommend for regular training.

Use these training weights as a starting point for your strength program. If your program calls for squats at 80 percent of 1RM, look up the 80% value and use that weight. Start conservatively and add weight once you can easily complete all prescribed reps with good form. This approach prevents ego lifting and reduces injury risk while still providing an appropriate training stimulus for strength development.

A one rep max (1RM) calculator estimates the maximum weight you can lift for a single repetition based on your performance with a heavier weight and lower reps. Your one rep max is a fundamental metric in strength training that indicates your absolute strength level and serves as the foundation for designing effective training programs.

Testing your true one rep max requires lifting maximally, which carries significant injury risk if done incorrectly or without proper preparation. A 1RM test should only be performed by experienced lifters who have developed proper technique and have a thorough warm-up. For most people, estimating your 1RM from a sub-maximal lift (3-10 reps) is safer and more practical. This calculator uses the proven Epley formula to provide an accurate estimate based on weight and reps you have actually lifted.

Once you know your estimated 1RM, you can use it to determine appropriate training weights for different goals and rep ranges. Strength coaches and training programs universally prescribe exercises as percentages of 1RM. For example, a program might call for squats at 80 percent of 1RM for 3 sets of 3 reps, which you can now calculate precisely. This percentage-based approach ensures your training intensity is appropriate for your current strength level and allows you to progress systematically over weeks and months.

The calculator also provides weights at common training percentages ranging from 60 percent to 95 percent of 1RM. These percentages correspond to different training goals: 60-70 percent is ideal for high-rep hypertrophy work, 75-85 percent develops strength and power, and 85-95 percent is for maximal strength and competition-specific training. Understanding these percentages allows you to train more intelligently and achieve your specific fitness goals.

This calculator uses the Epley formula to estimate your one rep max from a sub-maximal lift:

Epley Formula: 1RM = Weight × (1 + Reps ÷ 30)

Example Calculation: If you lift 185 pounds for 5 reps, your estimated 1RM is:

1RM = 185 × (1 + 5 ÷ 30) = 185 × 1.1667 = 215.7 pounds

Training Percentages: Once your 1RM is calculated, the training weights at different percentages are determined by multiplying your 1RM by the percentage decimal:

• 60% of 1RM = 1RM × 0.60
• 70% of 1RM = 1RM × 0.70
• 75% of 1RM = 1RM × 0.75
• 80% of 1RM = 1RM × 0.80
• 85% of 1RM = 1RM × 0.85
• 90% of 1RM = 1RM × 0.90 (Training Max)
• 95% of 1RM = 1RM × 0.95

The Epley formula is most accurate for rep ranges of 1 to 10. For rep ranges above 10, the estimates become progressively less accurate because the linear relationship between reps and intensity breaks down.

Example 1 — Bench Press 1RM Estimate: You complete a set of 5 repetitions on the bench press with 185 pounds. Using the Epley formula, your estimated 1RM is 185 × (1 + 5 divided by 30) = 215.7 pounds. Your training max (90% of 1RM) is 194 pounds. At 80% of 1RM, you would use 172 pounds for strength work. At 70% of 1RM, you would use 151 pounds for higher rep training.

Example 2 — Squat 1RM Estimate: You squat 315 pounds for 3 reps. Your estimated 1RM is 315 × (1 + 3 divided by 30) = 346.5 pounds. Your training max is 312 pounds. For a program calling for 75% of 1RM, you would use 260 pounds. For accessory work at 60% of 1RM, you would use 208 pounds.

Example 3 — Deadlift 1RM Estimate: You deadlift 405 pounds for a single rep. Technically this is already your 1RM, but we can note your training max at 90% would be 365 pounds. For training at 85% of 1RM, you would use 344 pounds. For hypertrophy work at 70% of 1RM, you would use 284 pounds. A structured program might cycle through these percentages over weeks to develop different qualities of strength.