One Rep Max
1RM Calculator
Estimate your one rep max from a submaximal lift. Enter the weight you lifted and how many reps you completed — the calculator uses both the Epley and Brzycki formulas so you can compare results.
How the any lift 1RM calculator works
This calculator estimates your one rep max using two widely-used formulas. You enter the weight you lifted and the number of reps you completed, and the calculator works backwards to predict the heaviest single rep you could perform.
The Epley Formula
Developed by Boyd Epley, this is one of the most commonly used 1RM prediction equations. Tends to produce slightly higher estimates at higher rep ranges (above 10 reps).
1RM = weight × (1 + reps ÷ 30)The Brzycki Formula
Created by Matt Brzycki, this formula is slightly more conservative and is often preferred for lower rep ranges. Becomes invalid at 37 or more reps.
1RM = weight × (36 ÷ (37 − reps))Which formula is more accurate?
Neither is universally better. For rep ranges of 1–6 both produce very similar results. Above 10 reps, Epley tends to overestimate slightly. This calculator shows both so you can compare.
Using the percentage table
The training percentage table shows what weight to use for different intensities based on your estimated 1RM. Most strength programmes prescribe working sets between 70–85% of 1RM, while hypertrophy work typically falls in the 60–75% range.
Frequently asked questions
What is a 1 rep max (1RM)?
A 1 rep max is the maximum weight you can lift for a single repetition with proper form. It is the standard measure of absolute strength used in strength training and powerlifting programmes.
How accurate are 1RM calculators?
Most accurate for rep ranges of 2–10. Accuracy decreases above 10 reps as the formulas were designed for lower rep ranges. For the best estimate, use a weight you can lift for 3–5 reps.
What is the difference between the Epley and Brzycki formulas?
Both estimate your 1RM from submaximal effort. The Epley formula tends to give slightly higher estimates at higher rep ranges. The Brzycki formula is considered more conservative and is often more accurate for reps under 10.
Should I test my actual 1RM?
Testing a true 1RM carries injury risk and requires a spotter. Estimating from a 3–5 rep max is safer and nearly as accurate for programming purposes. Most coaches recommend using a calculator rather than maxing out regularly.
How do I use my 1RM to set training weights?
Use the percentage table below your result. Most strength programmes prescribe working sets at 70–85% of your 1RM. Hypertrophy training typically uses 60–75%. The table shows the exact weight for each percentage.