How much can you lift at maximum? The one-rep max (1RM) is the heaviest weight you can lift for a single repetition with proper form. It's the most important metric in strength training for planning training loads and tracking progress.
In this article, you'll learn how to safely estimate your 1RM from submaximal sets, which formulas exist, and how to use the results for your training.
What Is the One Rep Max?
The one-rep max (1RM) describes the maximum weight you can lift for exactly one repetition on a given exercise. It serves as the reference for training programming: percentages of your 1RM determine how heavy you should train across different rep ranges.
Rather than testing your true maximum (high injury risk), most athletes use estimation formulas. You lift a weight for multiple reps and calculate your 1RM from that.
The Four Formulas
Epley (Default)
1RM = weight × (1 + reps / 30)
The most widely used formula. Works well for 2–10 reps.
Brzycki
1RM = weight × 36 / (37 − reps)
Produces similar results to Epley at low rep counts, diverges at higher reps.
Lombardi
1RM = weight × reps0.10
An exponential approach that estimates more conservatively at high rep counts.
O'Conner
1RM = weight × (1 + reps × 0.025)
A simple linear formula. Tends to estimate slightly lower than Epley.
Example Calculation
Example: You bench press 100 kg for 5 reps:
| Formula | Estimated 1RM |
|---|---|
| Epley | 117 kg |
| Brzycki | 113 kg |
| Lombardi | 117 kg |
| O'Conner | 113 kg |
The formulas typically fall within a 5% range. For training programming, use the average or the most conservative estimate.
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Use your 1RM to calculate training weights for different goals:
| % of 1RM | Reps | Training Goal |
|---|---|---|
| 90–100% | 1–3 | Max strength |
| 80–90% | 3–6 | Strength |
| 70–80% | 6–12 | Hypertrophy |
| 50–70% | 12–20 | Muscular endurance |
Tips for Accurate Results
1. Use 3–8 reps: The formulas are most accurate in this range. Beyond 10 reps, estimation error increases.
2. Strict form: Only with proper technique will the results be realistic. Cheated reps skew the estimate.
3. Test while fresh: Perform the test at the beginning of your workout, not after fatigue. A proper warm-up is essential.
4. Update regularly: Your 1RM changes with training. Retest every 4–6 weeks to adjust your working weights.
1RM and Nutrition
Your strength potential also depends on nutrition. Adequate protein supports muscle building and recovery. Combine your 1RM training with an appropriate calorie burn estimate and your TDEE.
Conclusion
Your one rep max is the foundation for effective training programming. Use our 1RM Calculator for a quick estimate with four formulas and a percentage chart. Combine the result with your protein intake and macros for optimal results.