Free 1RM Calculator: Estimate Your One-Rep Max Instantly
Unlock a smarter way to train with our free One-Rep Max (1RM) Calculator. By estimating your 1RM from a submaximal set, you can safely and accurately design a **percentage-based training program** for effective **progressive overload**. Stop guessing your numbers and start building a data-driven plan to achieve your strength and hypertrophy goals.
1. Your Lift
2. Settings
Units
3. Your 1RM
How to Use 1RM for Progressive Overload
Your 1RM is the key to unlocking **percentage-based training**, a cornerstone of effective progressive overload. Instead of lifting to failure on every set, you work within specific intensity zones defined by percentages of your 1RM. This stimulates muscle growth and strength gains more sustainably.
Rep Strength and Percentage Chart
This chart shows the general relationship between the percentage of your 1RM and the number of reps you can likely perform. Use it to structure your workouts.
| % of 1RM | Estimated Reps | Primary Training Goal |
|---|---|---|
| 90-100% | 1-3 | Maximal Strength & Power |
| 80-90% | 4-6 | Strength & Hypertrophy |
| 70-80% | 8-12 | Hypertrophy (Muscle Growth) |
| 60-70% | 12-15+ | Muscular Endurance |
Comparison of 1RM Prediction Formulas
While dozens of 1RM prediction formulas exist, most calculators use one of three popular, scientifically-validated equations: Brzycki, Epley, or Lander. Our calculator defaults to the Brzycki formula but allows you to compare results from all three.
| Formula | Equation | Notes |
|---|---|---|
| Brzycki | Weight / (1.0278 - (0.0278 * Reps)) | Considered highly accurate for rep ranges up to 10. |
| Epley | Weight * (1 + (Reps / 30)) | A simpler linear formula, often used for its ease of calculation. |
| Lander | (100 * Weight) / (101.3 - (2.67123 * Reps)) | Another well-regarded formula that provides results similar to Brzycki. |
The accuracy of these formulas has been validated in numerous studies, including a comprehensive comparison in the Journal of Strength and Conditioning Research.
How to Safely Perform a Submaximal Test
Using a submaximal test (lifting a weight for multiple reps) is much safer than attempting a true 1-rep max. Follow this protocol for an accurate and safe test.
Scientifically Reviewed By
This article and calculator have been reviewed for scientific accuracy by the BulkRoutine Team. Our team includes certified Strength and Conditioning Specialists (CSCS), registered dietitians (RD), and exercise physiologists who ensure our content is evidence-based and up-to-date.