1RM Calculator Know Your Max.

Calculate your one rep max for free. Enter weight and reps to get instant 1RM estimates with Epley & Brzycki formulas and a full percentage-based training table.

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Features

Everything you need to
train with precision

Instant Calculation

Science-backed formulas. Enter your data and get your estimated 1RM in seconds.

Percentage Table

Plan every set with precision. Loads at 65%, 75%, 85% are all calculated instantly.

How it works

Science-backed 1RM
estimation formulas

Epley Formula

The most widely used 1RM formula in strength training. Most accurate for 1–10 rep ranges.

1RM = W × (1 + R / 30)

Where W = weight lifted and R = reps performed

Brzycki Formula

A popular alternative that performs well across higher rep ranges (up to 15 reps).

1RM = W × 36 / (37 − R)

Where W = weight lifted and R = reps performed

Research from the National Strength and Conditioning Association (NSCA) confirms both formulas provide reliable 1RM estimates, with the Epley formula showing slightly higher accuracy for lower rep ranges and the Brzycki formula performing better for higher rep sets.

FAQ

Frequently asked
questions

What is a 1RM (one rep max)?
Your one rep max (1RM) is the maximum amount of weight you can lift for a single repetition with proper form. It is the gold standard for measuring maximal strength in weightlifting and powerlifting. Knowing your 1RM allows you to train at precise percentages for optimal strength gains.
How do you calculate 1RM without maxing out?
Submaximal 1RM estimation formulas predict your one rep max based on the weight you lifted and the number of reps performed. You do not need to attempt a dangerous maximal lift. The Epley formula (1RM = W × (1 + R / 30)) and Brzycki formula (1RM = W × 36 / (37 − R)) are research-validated methods that work perfectly for rep ranges up to 10-15.
Is the 1RM calculator app free?
Yes! The 1RM app is completely free to download on iOS and Android with no hidden fees, subscriptions, or in-app purchases. Get unlimited 1RM estimates and automatic percentage-based training tables at no cost.
What training percentages can I get from my 1RM?
Once your 1RM is calculated, the app generates a complete training table with loads at every percentage from 50% to 95%. Common training zones include: 65-75% for hypertrophy (8-12 reps), 75-85% for strength (5-8 reps), and 85-95% for peaking (1-5 reps). This takes the guesswork out of planning your workouts.
Which 1RM formula is most accurate?
The Epley formula is most accurate for 1-10 rep ranges and is the most widely used in the strength community. The Brzycki formula works well for higher rep ranges (up to 15). Research shows both have a strong correlation with actual 1RM testing. The 1RM app shows you results from both formulas so you can compare.