One-Rep Max (1RM) Calculator: What It Is and How to Use It

What Is One-Rep Max (1RM)?

Your One-Rep Max (1RM) is the maximum amount of weight you can lift for a single repetition of an exercise with proper form. It is a crucial measure of strength and progress in weight training, particularly for exercises like the bench press, squat, deadlift, and overhead press.

Why Is 1RM Important?

• Measures Strength Progress – Tracking 1RM over time helps gauge improvements in strength and performance.
• Guides Workout Intensity – Knowing your 1RM allows you to determine appropriate weight percentages for different training goals (e.g., strength, hypertrophy, endurance).
• Prevents Overtraining – Helps avoid lifting too heavy, reducing the risk of injury.
• Optimizes Training Programs – Many training routines use 1RM percentages to structure workouts effectively.

How to Calculate Your 1RM

Since testing your 1RM by lifting a maximum weight can be risky, especially without a spotter, you can estimate it using a formula. The Epley formula is the most commonly used method:

1RM = W × (1 + r / 30)

Where:

• W = Weight lifted
• r = Number of reps performed (should be ≤10 for best accuracy)

Example Calculation

If you can bench press 80 kg for 5 reps, your estimated 1RM is:

1RM = 80 × (1 + 5/30) = 80 × 1.1667 = 93.3 kg

So, your estimated 1RM is 93.3 kg.

Online 1RM Calculator

To simplify the process, use our One-Rep Max Calculator:

Simply enter the weight lifted and the number of reps, and the calculator will estimate your 1RM instantly!

1RM-Based Training Percentages

• Strength Training (1-5 reps): 85-100% of 1RM
• Hypertrophy (Muscle Growth, 6-12 reps): 65-85% of 1RM
• Muscular Endurance (12+ reps): 50-65% of 1RM

Related Terms

1. Training Volume

Total amount of weight lifted during a session (sets × reps × weight). Example: 4 sets of 10 reps at 50 kg = 2000 kg total volume.

2. Progressive Overload

Gradually increasing weight, reps, or intensity over time to build strength.

3. Repetition Maximum (RM)

The most weight you can lift for a specific number of reps. Example: 5RM = Heaviest weight you can lift for 5 reps.

4. Failure vs. Submaximal Training

Training to Failure: Lifting until no more reps are possible.

Submaximal Training: Lifting below failure to focus on endurance and form.

Additional Fitness Tools & Calculators

• BMI Calculator & Ideal Weight
• Calorie Calculator
• BMR & TDEE Calculator
• Body Fat Percentage Calculator
• Lean Body Mass (LBM) Calculator
• Waist-to-Hip Ratio Calculator

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• 5 Biggest Weight Loss Myths You Need to Stop Believing
• Best Foods for Fat Loss: What to Eat & What to Avoid
• How to Start Strength Training: A Beginner’s Guide

Final Thoughts

Understanding and using your One-Rep Max (1RM) is essential for effective strength training. Whether you’re looking to build muscle, gain strength, or improve endurance, knowing your 1RM helps you train smarter and reach your goals faster. Use our 1RM Calculator to track your progress and optimize your workouts!