Free One Rep Max Calculator

What is a One Rep Max Calculator?

A One Rep Max (1RM) Calculator estimates the maximum weight you can lift for a single repetition of any exercise, helping you train smarter, track progress, and set appropriate weights for your workouts without risky max-out attempts.

Formulas Used in This Calculator

Our calculator implements five scientifically-developed formulas to estimate your 1RM:

Epley Formula: 1RM = w × (1 + r/30)
Brzycki Formula: 1RM = w × (36 / (37 - r))
Lombardi Formula: 1RM = w × r^0.10
O’Conner Formula: 1RM = w × (1 + r/40)
Wathan Formula: 1RM = w × (100 / (48.8 + (53.8 × e^-0.075×r)))

How to Use the 1RM Calculator

1. Enter the weight you lifted (in pounds or kilograms)
2. Input how many repetitions you completed with that weight
3. Select your preferred formula (Epley is recommended for beginners)
4. View your estimated one-rep maximum
5. Use the generated table to plan your training weights for different rep ranges

Frequently Asked Questions

How accurate are 1RM calculators?
1RM calculators provide estimates that are generally within 5-10% of your actual max when using proper form and recent data.

Which formula is most accurate?
The Brzycki formula is often considered most accurate for lower reps (1-5), while Epley works well across broader rep ranges.

How often should I test my 1RM?
Most lifters shouldn’t test true 1RM more than every 3-4 months. Use calculated estimates for more frequent tracking.

Can I use this for all exercises?
These formulas work best for compound lifts like squats, bench press, and deadlifts. They’re less accurate for isolation exercises.

Terminology Explained

One Rep Max (1RM): The maximum amount of weight you can lift for one complete repetition of an exercise.

Repetitions (Reps): The number of times you complete a movement in one set.

Training Percentage: The percentage of your 1RM used for a specific training purpose (e.g., 80% of 1RM for strength training).

Progressive Overload: Gradually increasing the stress on your musculoskeletal system to continue making gains.

Formula Technical Sources

The formulas in this calculator were developed by exercise scientists:

• Brzycki Formula: Developed by Matt Brzycki, strength coach at Princeton University
• Epley Formula: Developed by Boyd Epley, founder of the National Strength and Conditioning Association
• Lombardi Formula: Developed by V. Lombardi in exercise science research
• O’Conner Formula: Based on the work of B. O’Conner and colleagues
• Wathan Formula: Developed by D. Wathan as a more modern approach to 1RM estimation

Important Safety Notes

1. Never attempt a true 1RM without proper spotting and safety equipment
2. Always warm up thoroughly before heavy lifting
3. These calculations are estimates - individual results may vary
4. Consult with a healthcare professional before beginning any new training program
5. Focus on proper form over maximum weight to prevent injuries
6. Allow adequate recovery between heavy training sessions

Training Strategies to Improve Your 1RM

1. Periodization: Vary your training intensity and volume over weeks/months
2. Strength-Specific Training: Include sets of 1-5 reps at 85-95% of your 1RM
3. Accessory Work: Strengthen supporting muscles that assist in your main lifts
4. Proper Nutrition: Ensure adequate protein intake and overall calories to support strength gains
5. Recovery: Prioritize sleep and rest days to allow muscles to repair and grow stronger

1RM Standards by Experience Level

Note: These are general guidelines for adult male lifters (in pounds)

Beginner (3-6 months training)

• Bench Press: 0.8-1.0x body weight
• Squat: 1.0-1.2x body weight
• Deadlift: 1.2-1.5x body weight

Intermediate (1-2 years training)

• Bench Press: 1.0-1.3x body weight
• Squat: 1.3-1.6x body weight
• Deadlift: 1.6-2.0x body weight

Advanced (3+ years training)

• Bench Press: 1.3-1.8x body weight
• Squat: 1.6-2.2x body weight
• Deadlift: 2.0-2.5x body weight