Last updated: 3 August 2026
Reviewed by Jordan Makin, FA Level 2 Football Coach
Estimate your 1RM
Why RPE matters for an accurate 1RM estimate
Most 1RM calculators assume every set you enter was an all-out maximal effort — but in practice, most working sets aren't. If you did 5 reps at a weight you could actually have pushed to 7 or 8 reps, a calculator that assumes it was your true max will underestimate your real 1RM.
Barbell Medicine's own 1RM tool is built specifically around this: it asks for RPE (Rate of Perceived Exertion) alongside weight and reps, because it's "unlike many 1RM calculators" that skip this adjustment entirely. This calculator does the same — select how many reps you genuinely had left in the tank, and the estimate adjusts accordingly by treating those reserve reps as if they'd been performed, before applying the Epley and Brzycki formulas.
Epley vs Brzycki — why two numbers?
This calculator shows both formulas because they're built on slightly different assumptions and can diverge, especially at higher rep counts:
- Epley formula — tends to run slightly higher at higher rep ranges (8+ reps), and is widely used across strength sport calculators.
- Brzycki formula — tends to be more conservative at higher rep counts, and some coaches consider it more reliable specifically in the 6-10 rep range.
Neither is definitively "more correct" — both are estimates, and the gap between them naturally widens as rep count increases. For low-rep sets (1-5 reps), the two formulas agree closely.
Top picks compared
| Pick | Product | Best for | |
|---|---|---|---|
| Top pick | Rogue Adjustable Dumbbell Set (Pair) | Essential for testing 1RM safely across multiple lifts. Adjustable design saves space. | Check price → |
| Option | Sorinex Safety Squat Bar | Safer 1RM testing on squats. Reduces injury risk while still letting you find true max. | Check price → |
| Option | Lifting Platform (8 ft) | Dedicated space for 1RM testing. Solid foundation reduces risk during heavy singles. | Check price → |
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Frequently asked questions
How many reps give the best estimate?
Sets of 3–6 reps give the most accurate 1RM estimates. Above ~10 reps, accuracy drops sharply.
Do I need to enter RPE?
No — it's optional. If you leave it at RPE 10 (the default), the calculator assumes your set was a genuine maximal effort. Only adjust it if you know the set wasn't all-out.
Which is more accurate, Epley or Brzycki?
Neither is universally more accurate — they're both estimates built on different assumptions, and they naturally agree more closely at low rep counts (1-5) and diverge more at higher rep counts (8+). Use whichever your coach or programme references, or take the average of the two.
How often should I retest my 1RM?
Most lifters retest every 4-8 weeks, since testing a true maximal effort too often adds unnecessary fatigue and injury risk without meaningfully more useful data than an estimate from recent training sets.