CalcLibrary

One-Rep Max Calculator

Estimate your one-rep max (1RM) from a sub-maximal set. Pick Epley, Brzycki, or Lombardi, enter the weight you lifted and the reps you completed, and get your 1RM plus training-load percentages from 75 % to 95 %.

Units
lb
Examples

A typical hypertrophy set used as a 1RM proxy.

Estimated 1RM
205.7 lb
95 % of 1RM
195.6 lb
90 % of 1RM
185.2 lb
85 % of 1RM
174.8 lb
80 % of 1RM
164.7 lb
75 % of 1RM
154.3 lb

In the 4–10 rep band where these formulas were originally fit.

Estimate only. Use proper form, warm up, and progress gradually. This calculator is not coaching or medical advice.

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Examples

How It Works

Formula

1RMEpley=w⋅(1+r30)\text{1RM}_{\text{Epley}} = w \cdot \left(1 + \frac{r}{30}\right)

1RMBrzycki=w⋅3637−r\text{1RM}_{\text{Brzycki}} = w \cdot \frac{36}{37 - r}

1RMLombardi=w⋅r0.10\text{1RM}_{\text{Lombardi}} = w \cdot r^{0.10}

Variables

ww

Weight lifted on the set(kg or lb)

rr

Reps completed(reps)

1RM\text{1RM}

Estimated one-rep maximum(kg or lb)

Enter the load you lifted, the number of clean reps you completed, and pick a formula. The calculator estimates the single-rep maximum that would have produced that set. From the 1RM we then derive five training-load percentages (95 / 90 / 85 / 80 / 75 %) so you can read a working weight off the same panel.

Frequently Asked Questions

01What is a one-rep max?
Your one-rep max (1RM) is the heaviest weight you could lift for a single, full repetition of a given exercise with good form. It's the standard reference point for strength programming — most workout templates prescribe sets at 70–95 % of 1RM.
02Why not just test my 1RM directly?
Testing a true 1RM cold is a bad idea. The lift takes a long warm-up, taxes the central nervous system, and the failure point is where injuries happen. Estimating from a sub-maximal set you can already do safely gives a working number without that risk.
03Which formula should I use — Epley, Brzycki, or Lombardi?
They are three different empirical curves. Epley is roughly linear and tends to predict slightly higher than Brzycki at higher reps. Brzycki uses a hyperbolic form and reads a bit lower past 5 reps. Lombardi uses a power curve and is often more conservative across the range. At lower rep counts, the three formulas often land in a similar range, but the estimate varies by exercise and lifter.
04How do I use the training-load percentages?
The percentages give you a working weight for different goals at a glance. Strength work commonly sits at 85–95 % of 1RM for low reps; hypertrophy is typically 70–85 % for moderate reps; speed and technique work runs lighter. Use the percentages as a starting point and adjust by feel — bar speed, form, and how the warm-ups moved should override the number on the bar.
05How accurate is the estimate?
Accuracy varies by exercise, lifter, and rep count. Estimates are usually more reliable at lower rep counts and get less reliable as reps climb past 10.

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