Estimate your maximal strength capacity using validated prediction models. Ideal for programming strength cycles, tracking progress, and designing periodized training.
Your one-repetition maximum (1RM) is the heaviest load you can lift for a single repetition with proper form. It is the ultimate metric for absolute strength and a cornerstone of periodized resistance training. Direct 1RM testing can be risky and fatiguing, especially for beginners or advanced athletes. That's where validated submaximal prediction formulas come in: they estimate your 1RM from a lighter set performed to technical failure (or near failure).
General regression: 1RM ≈ Weight × (1 + reps / 30) (Epley, 1985) is one of the most cited equations in sports science.
Research published in the Journal of Strength and Conditioning Research (Reynolds et al., 2006) indicates that the Epley and Brzycki equations provide the highest accuracy for predicting 1RM from submaximal tests (3–10 reps). For higher rep ranges (10–15), Lombardi or Mayhew equations may yield more realistic estimates. This calculator implements all major formulas to give you a comprehensive view — because individual anthropometry and training experience matter.
Pro tip: For best results, perform your test set with a controlled tempo, and avoid failure on high-risk lifts (e.g., squat, deadlift). Use predictions as a guide, not absolute truth.
Coaches use 1RM estimates to prescribe training intensities: hypertrophy zones (65‑80% of 1RM), strength zones (80‑90%), and peaking phases (>90%). This interactive calculator instantly converts your performance into relative intensities, helping you design evidence‑based microcycles. For example, if your estimated 1RM is 300 lbs, then 75% (225 lbs) becomes your working weight for 8‑12 reps during muscle‑building blocks.
| Training Goal | Intensity (% of 1RM) | Rep Range | Application |
|---|---|---|---|
| Neural Strength / Peaking | 90‑100% | 1‑3 reps | Powerlifting, maximal strength tests |
| Strength & Power | 80‑90% | 3‑6 reps | Strength phases, sports performance |
| Muscular Hypertrophy | 65‑80% | 6‑12 reps | Bodybuilding, muscle growth |
| Muscular Endurance | ≤65% | 12+ reps | Circuit training, metabolic conditioning |
A 32‑year old recreational lifter performed 225 lbs for 6 reps on the bench press. The calculator outputs: Epley 1RM = 270 lbs, Brzycki = 270 lbs, Lombardi = 282 lbs. Based on average ~274 lbs, the coach programmed a 8‑week cycle starting at 70% (192 lbs) progressing to 88% (241 lbs). After 8 weeks, the lifter successfully hit a true 1RM of 275 lbs — validating the prediction error of less than 1.5%.