One Rep Max Calculator
Estimate your 1RM from any set — Epley and Brzycki formulas.
The One Rep Max Calculator estimates the maximum weight you could lift for a single repetition from any set you have completed, using two standard formulas: Epley (1RM = weight × (1 + reps ÷ 30)) and Brzycki, an alternative that agrees closely at moderate rep ranges.
Estimating 1RM from submaximal sets is how smart lifters program intensity without risky maximal attempts: a 5-rep max of 80 kg suggests a 1RM near 93 kg, letting you plan percentages of that number safely. The tool also projects estimated maxes at other rep counts, handy for setting up training blocks.
Formulas assume technical proficiency and leave the last couple of reps in reserve; they overestimate for very high rep sets. Always warm up and use a spotter when approaching true limits. Runs locally in your browser.
Estimated 1RM
93.3 kg
Epley formula
Brzycki estimate
90.0 kg
alternative formula
Your input
80 × 5
leave 1–2 reps in reserve to be safe
Estimated maxes at other rep counts (Epley)
| 1 reps | ≈ 82.7 kg |
| 2 reps | ≈ 85.3 kg |
| 3 reps | ≈ 88.0 kg |
| 4 reps | ≈ 90.7 kg |
| 5 reps | ≈ 93.3 kg |
| 6 reps | ≈ 96.0 kg |
| 7 reps | ≈ 98.7 kg |
| 8 reps | ≈ 101.3 kg |
| 9 reps | ≈ 104.0 kg |
| 10 reps | ≈ 106.7 kg |
| 11 reps | ≈ 109.3 kg |
One-rep-max estimates from submaximal sets let you program intensity without risky maximal attempts — always warm up properly and use a spotter near limit.
How to use the One Rep Max Calculator
- Enter the weight you lifted and the repetitions you completed.
- Choose kilograms or pounds.
- Read your estimated 1RM from both formulas.
- Scan the projected maxes at other rep counts.
- Program training percentages from the estimate.
Frequently asked questions
What is the Epley formula?
1RM = weight × (1 + reps ÷ 30). Lifting 80 kg for 5 reps estimates a 1RM of 80 × 1.167 ≈ 93 kg. Brzycki (weight × 36 ÷ (37 − reps)) gives a similar figure and is preferred by some coaches at low rep ranges.
Are 1RM estimates accurate?
Within a few percent for experienced lifters at 1–10 reps. Estimates grow less reliable above ~12 reps (endurance clouds strength), and technique and fatigue on the day matter as much as the math.
Should I test my true 1RM?
Only with proper warm-up, a spotter and experience near limit — true maxes carry the highest injury risk. Most programming needs only the estimate, which this calculator provides safely.
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