One Rep Max Calculator · Practical guide
Epley vs. Brzycki Formula
The two most popular 1RM formulas, compared with real numbers.
At a glance
Two Classics, Two Shapes
The Epley formula, 1RM = weight × (1 + reps ÷ 30), assumes every extra rep adds a fixed slice of strength — a straight line. Brzycki, 1RM = weight ÷ (1.0278 − 0.0278 × reps), curves upward, so its estimate climbs faster as reps increase.
Interactive tool
One Rep Max Calculator
Enter your own values, then compare the result with the examples below.
1RM Estimates
Percentage Table
| % of 1RM | Weight | Typical Use |
|---|
Same Set, Different Estimates
Enter 225 lbs at various rep counts and the two formulas track each other closely through the low and moderate rep ranges:
| Reps at 225 lbs | Epley | Brzycki |
|---|---|---|
| 3 | 247.5 lbs | 238.2 lbs |
| 5 | 262.5 lbs | 253.1 lbs |
| 10 | 300.0 lbs | 300.1 lbs |
Which Should You Trust?
For sets of 1–10 reps the two estimates stay within a few percent of each other, and Brzycki is widely used in that range. Past 10 reps both become less reliable — fatigue and muscular endurance distort the relationship — which is why this calculator shows four formulas instead of crowning one winner.
The Practical Takeaway
Pick the formula that best matched your last true max and stick with it for consistency, or simply train off the four-formula average shown in the results. Progress comes from tracking the same number over time, not from the formula you choose.
Frequently Asked Questions
Is Epley or Brzycki more accurate?
Brzycki is widely used and accurate for moderate rep ranges of 1-10. Comparing multiple formulas, as this calculator does, gives the most reliable picture.
Do Lombardi and Mayhew use the same inputs?
Yes. All four formulas need only the weight lifted and the reps performed, so the calculator can show all of them from a single entry.
Why do estimates diverge above 10 reps?
High-rep sets measure muscular endurance as much as maximum strength, and each formula handles that trade-off differently. Predictions past 10-12 reps should be treated as rough.
Can I use these formulas for a set of 1?
If you truly lifted the weight once, that is your 1RM by definition. The formulas are designed for submaximal sets of 2-10 reps.