When to use this calculator
Estimate one-repetition maximum from a submaximal lifted load and repetition count. A rough performance estimate, not an instruction to attempt the predicted load. Equation accuracy varies by lift and person.
Explore the training quantities calculators for other questions in this topic. For a related calculation, use the Race Percentage Improvement Calculator: Measure the relative reduction in elapsed race time.
PUTTING IT INTO PRACTICE
One Rep Max: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Lifted load (kg) | 100 |
| Repetitions (integer) | 5 |
| Prediction equation | epley |
| Result | 116.666667 kg |
- Check the input labels and enter the example values above.
- Apply the relationship: Epley = load(1+reps/30); Brzycki = load×36/(37−reps)..
- The result is 116.666667 kg, rounded for display.
How to interpret your result
A rough performance estimate, not an instruction to attempt the predicted load. Equation accuracy varies by lift and person.
Use a consistent definition of load. Repetition volume does not capture effort, range of motion or recovery. Ratios and totals are descriptive records rather than personalised health or injury predictions.
Frequently asked questions
Does a training ratio establish a safe workload?
No. A simple ratio cannot establish safety or account for individual conditioning, recovery and injury history.
When is the one rep max calculator useful?
Estimate one-repetition maximum from a submaximal lifted load and repetition count. A rough performance estimate, not an instruction to attempt the predicted load. Equation accuracy varies by lift and person.
How do I use the one rep max calculator?
Enter lifted load (kg), repetitions (integer), prediction equation. The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Epley = load(1+reps/30); Brzycki = load×36/(37−reps)..
What should I check before using the result?
A rough performance estimate, not an instruction to attempt the predicted load. Equation accuracy varies by lift and person.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
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