Strength training
Brzycki Formula: Accurate 1RM Calculation
The Brzycki formula stands out for its accuracy in the low rep range, ideal for estimating maximal strength.
What the Brzycki formula is and where it comes from
The Brzycki formula, developed by Matt Brzycki, is a classic reference for estimating one-rep max. It became popular in strength training for delivering especially reliable estimates when working with few reps.
Unlike purely linear models, Brzycki uses a relationship that fits the real strength-decay curve under fatigue in short sets well, which makes it a favorite among strength coaches.
The formula and how to apply it step by step
The Brzycki equation is: 1RM = weight × 36 / (37 − reps). You need the weight moved and the reps performed close to technical failure.
Worked example: a client benches 170 kg for 4 reps. 1RM = 170 × 36 / (37 − 4) = 6120 / 33 = roughly 185.5 kg. For a heavy reference set, Brzycki returns about 200 kg, a more conservative estimate than Epley.
Important: because the denominator is (37 − reps), the formula breaks down as you approach 37 reps. That is why it should only be used in low and medium ranges.
When to use the Brzycki formula
Brzycki is especially accurate in the 1 to 10 rep range, which makes it ideal for heavy strength-oriented sets. The closer you are to a real 1RM, the better it performs.
Strength
High accuracy in the 1 to 10 rep range, the most relevant for maximal strength work.
Limitation
It distorts on long sets and becomes invalid near 37 reps because of the denominator structure.
Best use case
Submaximal strength tests with 3-6 reps on heavy compound lifts.
Comparison with the other four formulas
For the same heavy reference set, estimates vary: Brzycki returns about 200 kg, just like Lombardi, while Lander gives 202.8 kg, O'Conner 205 kg and Epley 206.7 kg.
Brzycki usually lands on the conservative side of the range, which protects against prescribing loads that are too high. Pairing it with Epley gives you an interval: the client's true value tends to fall between the two estimates.
How to use 1RM in your clients' programming
With a reliable 1RM you can prescribe strength blocks at high percentages (85-95%) knowing you are not overestimating the load. Adjust with low RIR (1-2) on heavy sets to keep technical quality.
In TrainerStudio you assign the estimated 1RM, generate percentage-based loads and log every attempt to confirm whether the estimate holds in practice and adjust the plan accordingly.