Health & Fitness
1RM Formula Comparison Calculator
Compare Brzycki, Epley, Lombardi and O'Conner one-rep-max estimates from the same set.
Preparing your result…
What this calculator does
Calculates 1RM Formula Comparison Calculator using the formula verified against the cited source.
What your result means
An estimate from the inputs you enter, within the scope stated below — not advice.
Formula
Brzycki: w×36÷(37−r); Epley: w×(1+r÷30); Lombardi: w×r^0.10; O'Conner: w×(1+0.025r)
The step-by-step working for your own numbers appears with the result above and in the PDF report.
Frequently asked questions
Symbols and assumptions
- Inputs
- The values entered in the fields above
- • Common estimated-1RM variants: Brzycki W×36/(37−r); Epley W×(1+r/30); Lombardi W×r^0.10; O’Conner W×(1+0.025r). Load W and result use the same unit; r is completed repetitions.
Sources and review
Reviewed 2026-10-18 · Next review 2027-04-18
- • Original comparative research Table 1 reproduces equations with rounded coefficients (Brzycki 1.0278−0.0278r and Epley 0.033r); document the exact chosen variant instead of claiming rounded forms are identical. Avoid high-repetition extrapolation and nonpositive denominators. Predictions differ by exercise and sample.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Quick reference
| Scenario | Weight lifted (kg) | Repetitions completed (reps) | Average estimated 1RM |
|---|---|---|---|
| Worked example | 100 | 5 | 114.7821 kg |
| Half the amounts | 50 | 5 | 57.3911 kg |
| Double the amounts | 200 | 5 | 229.5643 kg |
Need the full picture? Get the detailed PDF report with charts, tables, formulas and working steps.
Reviewed 2026-10-18 · Next review 2027-04-18
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