One-Rep Max (Brzycki)
Estimated one-rep max, an alternative to Epley.
Formula
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Example
100 kg × 5 reps ⇒ 112.5 kg
How it works
This formula estimates the maximum weight a person could lift for a single repetition by starting from a lighter set performed to failure and scaling it upward. The Brzycki equation is based on the observed relationship that, as reps increase, the percentage of true 1RM you can handle decreases in a fairly predictable way for many lifts. It is an estimate, not a direct measurement, so it works best for moderate rep ranges and controlled, technically sound lifts.
When to use it
Use this when you want a quick estimate of 1RM without asking someone to attempt a true maximal lift, such as in training plans, testing sessions, or comparing strength over time. It is especially useful in gym programming for compound lifts when you have a recent set taken close to failure.
Worked example, step by step
Suppose an athlete lifts 80 kg for 8 reps. 1RM = w × 36 / (37 - r) 1RM = 80 × 36 / (37 - 8) 1RM = 80 × 36 / 29 1RM = 2880 / 29 1RM ≈ 99.3 kg
Common mistakes to avoid
- Using a rep set that was far from failure, which makes the estimate too low
- Applying the formula to very high rep counts where it becomes less reliable
- Treating the estimate as an exact 1RM instead of an approximation
Did You Know?
Brzycki's formula gives slightly lower numbers than Epley's at high rep counts, so lifters often compare both.
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