1RM Calculator
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One Rep Max Calculator

1RM Calculator

What is a One Rep Max?

Your One Rep Max (1RM) is the theoretical limit of maximum weight you can lift for a single, clean repetition. It serves as the baseline for all percentage-based training, ensuring every set you perform is optimized for your specific goals suitable for powerlifting and bodybuilding.

Scientific Formulas
Instant Analysis

Looking for Deadlift specifics?

Use our Specialized Deadlift 1RM Calculator

Why it matters

  • ✓Track strength gains securely without maxing out every week.
  • ✓Calculate precise loads for hypertrophy (70-80%) vs strength (85%+).
  • ✓Prevent injury by avoiding ego-lifting failure.

Behind the Math

E

Epley Formula

1RM = Weight × (1 + Reps/30)

The industry standard for 3-10 rep ranges. It tends to be slightly more optimistic but highly accurate for experienced lifters performing compound movements such as the bench press.

B

Brzycki Formula

1RM = Weight / (1.0278 - 0.0278 × Reps)

Known for its reliability across wider rep ranges. It can be more conservative as reps increase, often favored for safety-focused estimations in strength training programs.

Train Smarter, Not Harder

Stop guessing. Percentage-based training allows you to target specific physiological adaptations. Use our 1RM calculator to precisely calculate your working sets.

Learn more about 1RM-based Periodization
70%

Hypertrophy

8-12 Reps • Muscle Growth

85%

Strength

1-5 Reps • Force Production

95%

Peaking

1-3 Reps • Max Effort

Common Questions

Is this accurate for beginners?

Yes, but technique consistency is key. Beginners might find their 1RM fluctuates rapidly as neural efficiency improves. We recommend re-testing every 4-6 weeks using this one rep max calculator.

See full beginner 1RM guide

Which lifts should I calculate?

Focus on the "Big Three": Squat, Bench Press, and Deadlift. Overhead Press is also a great candidate. Isolation exercises (like curls) are less suitable for 1RM testing.

Bench Press 1RM Calculator Squat 1RM Calculator Deadlift 1RM Calculator

How often should I test my 1RM?

We recommend testing your One Rep Max every 8-12 weeks. Testing too frequently can drain your Central Nervous System (CNS) and increase injury risk. Use sub-maximal testing in between cycles.

Is 1RM training safe?

1RM testing is generally safe for experienced lifters with good form. Beginners should stick to "technical maxes" or predicted 1RMs using our calculator to avoid injury ensuring safety.

Comprehensive 1RM Guide

Why Calculate Your One Rep Max?

Knowing your One Rep Max (1RM) is crucial for designing an effective training program. It allows you to:

  • Determine appropriate weights for hypertrophy (muscle growth) vs. strength training.
  • Track your strength progress over time without constantly testing maximal loads.
  • Prevent injury by avoiding testing heavier weights than you can handle safely.

Understanding the Formulas

Our calculator uses two of the most scientifically validated formulas:

1. The Epley Formula: Developed in 1985, this is widely considered the standard for general lifting. It is particularly accurate for rep ranges between 3 and 10. We recommend this for most compound movements like the Bench Press and Squat.

2. The Brzycki Formula: Another popular method that helps mitigate the exponential scaling of other formulas. It is often preferred for converting higher rep sets (10+) into a 1RM estimate, though accuracy inherently decreases as reps increase beyond 10.

Safety Guidelines

While 1RM calculations are useful tools, they are estimates. Always ensure you:

  • Have a spotter when testing near-maximal loads.
  • Warm up thoroughly before any heavy lifting session.
  • Maintain proper form; if your form breaks down, the rep shouldn't count toward your calculation.