One Rep Max (1RM) Epley & Brzycki
Estimate max single lift from submaximal weight and reps. Average Epley and Brzycki for stability, cap reps 1-12. Table gives rep percentages for programming. Beyond 10 reps estimates turn to noise: test a 3-5RM and recalculate instead.
TL;DR
- Epley w×(1+r/30), Brzycki w×36/(37-r).
- Formulas: Epley: w×(1+r/30) | Brzycki: w×36/(37-r)
- 80kg×6 — Epley 96
How it works
Epley w×(1+r/30), Brzycki w×36/(37-r). Average them; beyond 10 reps noise increases. Table backs down ~3-4% per rep. To program at 80% take 1RM×0.8: on a 100 max that is 8-10 clean reps.
The math
80kg×6 →Epley96, Brzycki92.9 avg94.5. 5RM≈79. Inverse: weight≈1RM/(1+reps/30).
Average for robustness; cap 12 reps.
Examples
80kg×6
- Epley 96
- Avg 94.5
- 5RM ≈79
100kg×3
- Epley 110
- Brzycki 105.9
- Avg ≈108
When to use it
✦ Programming
Set loads without max test.
✦ Tracking
Progress without injury.
✦ Templates
Percentage-based progressions.
⚠ Common mistakes
- Testing true 1RM weekly
- Using >10 reps for estimate
- Estimating from sets to failure
FAQ (7)
Epley vs Brzycki?
Average; Epley conservative high reps.
Reps from 1RM?
Weight≈1RM/(1+reps/30).
Over 12 reps?
Unreliable estimate, test a 5RM.
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They're solid estimates using published formulas (WHO for BMI, Mifflin-St Jeor for BMR, CKD-EPI for GFR) but they're not a diagnosis. Think of them as a conversation starter: good for tracking trends, but your GP or nephrologist should interpret GFR, heart age or pregnancy dates with labs and context. We link the sources at the bottom for that reason.
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Sources & References
How this calculator is maintained
This calculator is written and maintained by Davide Coronese, independent developer and founder of CalcTracker.
Methodology: every formula is checked against official publications and validated by an automated test suite before release. Health, tax and finance pages cite the exact sources they rely on.
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