One Rep Max Calculator

What is the One Rep Max Calculator?

Estimate your one-rep max from a weight and reps performed, using the Epley and Brzycki formulas. Estimating a one-rep max from a submaximal set lets you plan percentage-based training without risking a true maximal lift.

How to use the One Rep Max Calculator

1. Enter your weight lifted, your reps completed.
2. Results update automatically as you type; you can also press Calculate.
3. Read the output: epley 1rm, brzycki 1rm, training loads.
4. Use the 📊 chart to see the result visually, then copy or share it.

Formula and method

Worked example

With weight lifted = 100 kg/lb, reps completed = 5, the One Rep Max Calculator returns epley 1rm: 116.7; brzycki 1rm: 112.5.

Where the One Rep Max Calculator helps in real life

You squatted 100 kg for five solid reps. The Epley and Brzycki estimates give your likely single-rep max, which your program uses to set training weights.

You train alone at home without a spotter. Estimating your max from a set of five is much safer than attempting a heavy single.

Common mistakes to avoid

• Using a set of 15 or more reps, where estimates become unreliable.
• Counting reps with poor form toward the estimate.
• Testing true maxes without a spotter or safety bars.
• Treating the two formulas as exact.

💡 Practical tip: Estimates are most reliable from sets of about 3–8 reps taken close to, but not past, technical failure.

Tips for better results

• Use sets of about 3–8 reps for the best estimates.
• Re-estimate every few weeks as you get stronger.
• Use safety bars or a spotter for heavy sets.

⚠️ This tool provides general information and is not medical advice. It is not a substitute for diagnosis or treatment by a qualified healthcare professional.

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