100 kg x 5 reps
- Epley
- 116.666666667 kg
- Brzycki
- 112.5 kg
- Training range 80%
- 93.3333333333 kg
One Rep Max Calculator
Use this free one rep max calculator to estimate 1RM with Epley and Brzycki formulas for strength training.
Research-based formula Estimate limits shown Examples included Private history
Formula steps
- Use the lifted weight and reps completed.
- Epley estimate = weight x (1 + reps / 30).
- Brzycki gives a second estimate for comparison.
How to use the one rep max calculator
- Enter the requested measurements, dates, lab values, or workout details.
- Check that the units and formula assumptions match what the tool is asking for.
- Press the calculate button to see the answer, supporting metrics, and formula steps.
- Read the estimate with the health disclaimer in mind, then copy the result if you need it for notes.
Common uses
Estimate a one-rep max without testing a true max.
Compare Epley and Brzycki estimates.
Plan training percentages from a recent rep set.
Track strength changes over time.
Examples
Estimated 1RM about 117 kg
Estimated 1RM about 154 kg
Estimated 1RM about 76 kg
Frequently asked questions
Quick answers about formulas, inputs, estimate limits, professional guidance, examples, and private in-browser history.
What can I use the One Rep Max Calculator for?
Use it for quick educational estimates, planning, comparison, and trend checks. Health and fitness results should be interpreted with context, not as a diagnosis.
How does the One Rep Max Calculator calculate the result?
The main estimate uses Epley: one-rep max = weight x (1 + reps / 30). Brzycki is shown as a comparison.
Is this medical advice?
This is training math, not a safety guarantee. Do not attempt heavy max lifts without appropriate technique, equipment, and supervision.
Are my health inputs private?
Yes. The calculator runs in your browser tab. Recent answers stay only on the page while you use it and are not sent to a server.