One Rep Max (1RM) Calculator

Weight
Reps

Your One-Rep Max (one-rm): ?

95%: ?
90%: ?
85%: ?
80%: ?
75%: ?
70%: ?
65%: ?
60%: ?
55%: ?
50%: ?

1RM Calculator – One Rep Max Estimator for Strength Training

One Rep Max Calculator

The 1RM Calculator (One Rep Max Calculator) helps you estimate the maximum weight you can lift in a single repetition for any strength training exercise like bench press, squat, deadlift, or pull-ups. Knowing your 1RM is essential for tracking progress, designing effective workout routines, and improving overall strength. This tool supports multiple scientific formulas to calculate your estimated 1RM based on weight lifted and number of repetitions.

How to Use the 1RM Calculator

Simply enter the weight you lifted and the number of reps completed (up to 10). The calculator will instantly estimate your One Rep Max using formulas like Epley, Brzycki, and more. You can use the result to set training loads at 60%, 75%, 90%, or 100% intensity based on your fitness goal.

Common Formulas Used to Estimate 1RM

Our calculator uses the most accurate and widely accepted formulas:

  • Epley Formula: 1RM = weight × (1 + reps ÷ 30)
  • Brzycki Formula: 1RM = weight × (36 ÷ (37 - reps))
  • Lombardi Formula: 1RM = weight × reps0.10
  • Mayhew et al. Formula: 1RM = (100 × weight) ÷ (52.2 + 41.9 × e-0.055 × reps)
  • O’Conner Formula: 1RM = weight × (1 + 0.025 × reps)
  • Wathan Formula: 1RM = (weight × 100) ÷ (48.8 + 53.8 × e-0.075 × reps)

Why You Should Track Your One Rep Max

  • Progress Tracking: Monitor strength gains over time.
  • Workout Planning: Build programs based on % of your 1RM.
  • Injury Prevention: Avoid lifting beyond your capacity.
  • Personal Records: Set and break lifting PRs with precision.

What is 1RM and Why It Matters

1RM, or One Repetition Maximum, is a standard measure of strength in resistance training. It's the highest amount of weight you can lift for one full repetition while maintaining proper form. Calculating your estimated 1RM lets you create personalized training plans. For example, if your 1RM on the bench press is 100kg, you might train at 75kg for 10 reps (75% intensity). This approach is useful in bodybuilding, powerlifting, and general fitness.

You can use your 1RM to adjust your volume, optimize hypertrophy, or assess progress in a bulking or cutting phase. It also helps balance your body weight-to-strength ratio, track number of reps improvements, and prevent overtraining.

Frequently Asked Questions (FAQs)

Is this 1RM calculator accurate?

Yes, our calculator uses proven scientific formulas like Epley, Brzycki, and Lombardi to estimate your One Rep Max. While it’s not a substitute for real-world testing, it gives a highly reliable result for most users.

How many reps should I enter for the best result?

For best accuracy, enter between 1 to 10 reps. Most formulas are highly accurate within the 3–5 rep range. Higher rep ranges may reduce precision.

Can I use this calculator for any exercise?

Yes, you can use it for exercises like bench press, deadlift, squat, shoulder press, barbell row, or even pull-ups. Just ensure you're using proper form during testing.

Is it safe for beginners to test their 1RM?

Beginners should avoid true 1RM testing and instead use estimated calculators like this to guide their progress. Always prioritize form and safety before maxing out.

How often should I test or recalculate my 1RM?

It’s ideal to update your 1RM every 4–6 weeks to reflect your strength progress. This helps you adjust your training intensity and set new goals.


Also check out our tools: BMI Calculator, Calorie Calculator, to support your fitness goals.