Fitness & Health

One Rep Max Estimator (1RM)

Estimates your one-rep max from a lighter set you can actually finish. It runs both the Epley and Brzycki formulas, reports both plus their average, and prints a 50 to 95 percent training table.

How to use
  1. Enter the weight lifted and reps completed.
  2. Use the percentage table for your training zones.
  3. Keep reps under 10 for the best accuracy.
Reps
Estimated one-rep max
253.1 lb

Average of Epley & Brzycki from 225 lb × 5 reps

Epley formula
262.5 lb
Brzycki formula
253.1 lb
Heavy 5×5 (85%)
215.1 lb
Volume (70%)
177.2 lb
Estimates for general wellness, not medical advice. Check with a doctor or dietitian before acting on health figures.
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How it's calculated

1RM = average of Epley w(1 + r/30) and Brzycki w·36 ÷ (37 − r)

w = weight lifted, r = reps completed. Epley = w(1 + r/30), Brzycki = w·36/(37 − r); the result averages both. Suggested training loads = 85% and 70% of the 1RM.

Worked examples

WeightRepsEpley 1RMBrzycki 1RM
100 lb8127 lb124 lb
200 lb5233 lb225 lb
315 lb2336 lb327 lb

Common questions

Which formula should I trust?

Both are widely used. Brzycki tends to read lower at higher reps, so averaging the two gives a balanced estimate.

How do I use the percentage table?

It scales your 1RM to typical training loads, like 70 to 80 percent for hypertrophy and 90 percent or more for max strength.