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One Rep Max Calculator: Estimate Your 1RM Safely

This free one rep max calculator estimates the heaviest weight you could lift once from a lighter set. It uses three popular formulas and gives a table of training weights from 50 to 95 percent.

By Debmedia Technologies LLP · Kolkata, India · Updated

What Is It and When Do You Need It?

Your one rep max is the heaviest weight you can lift once. Programmes use percentages of it to set the weight for each set. Testing it directly is tiring and can be risky, so most people estimate it from a set of several reps.

Enter the weight and the number of reps in a hard set, and the tool estimates your max and lists the training weights for each percentage.

How to Use This Tool

  1. Enter the weight you lifted.
  2. Enter how many reps you completed with good form.
  3. Press Calculate.
  4. Use the percentage table to plan your sets.

How the Calculation Works

Epley: 1RM = weight × (1 + reps ÷ 30). Brzycki: 1RM = weight × 36 ÷ (37 − reps). Lombardi: 1RM = weight × reps^0.10. The result shown is the average of the three. The percentage table multiplies the estimated max by 50 to 95 percent.

Worked Example

Lifting 80 kg for 8 reps gives an Epley estimate of 101.3 kg, Brzycki 99.3 kg and Lombardi 98.5 kg. The average is about 99.7 kg, so 80% of it is about 79.8 kg.

Common Uses

  • Programme planning.
  • Tracking strength.
  • Setting safe training weights.
  • Comparing exercises.

Tips and Common Mistakes

  • Use a set taken close to failure.
  • Estimates are less reliable above 10 reps.
  • Use a spotter when lifting heavy.

Next, you may need the BMR and TDEE calculator, body fat calculator, running pace calculator, BMI calculator.

Everything runs in your browser. Nothing you type is uploaded, stored or sent to any outside service.

Frequently Asked Questions

It is the most weight you can lift for one full repetition with good form. It is used to set training loads.
They agree closely for low reps. Epley is common, Brzycki is popular for fewer than 10 reps, and Lombardi is used for higher reps. The tool shows all three and their average.
Testing needs a warm-up, good form and a spotter. An estimate from a lighter set is safer and usually good enough.
It is best with 2 to 8 reps. Results above 12 reps are unreliable.

Disclaimer: results are calculated in your browser from the numbers you enter. Check important results before you rely on them for money, health, safety or legal decisions.