One Rep Max Calculator
Calculate your 1RM using 7 validated formulas. Get training percentages, strength standards, and weight recommendations for any rep range.
Exercise Information
Most accurate for 1-10 reps. Enter the number of reps you completed to failure.
1 Rep Max Results
Formula Comparison
Formula Results
Training Loads
Training Percentage Guide
Strength Standards
Standards are approximate and based on body weight ratios for Bench Press
Safety Reminders
- • Always warm up thoroughly before attempting heavy lifts
- • Use a spotter for bench press and other potentially dangerous exercises
- • Only attempt true 1RM with proper supervision
- • These are estimates - your actual 1RM may vary
What is One Rep Max Calculator?
Understanding One Rep Max (1RM)
One Rep Max (1RM) is the maximum amount of weight you can lift for a single repetition with proper form. It's a key measure of strength and is used to determine training loads, track progress, and compare strength levels across different individuals.
Why 1RM Matters
- Provides an objective measure of maximum strength
- Used to calculate percentage-based training loads
- Helps track strength progress over time
- Important for powerlifting and strength sport competitions
- Guides program design and exercise selection
Estimation vs. Testing
While testing your true 1RM can be valuable, it's not always necessary or safe. Estimation formulas allow you to calculate your 1RM based on submaximal lifts (typically 3-10 reps), which is safer and can be done more frequently.
1RM Estimation Formulas
Epley Formula (Most Popular)
1RM = Weight × (1 + Reps ÷ 30)Developed in 1985, this is the most widely used formula. It works best for rep ranges of 1-10 and tends to be accurate for most people and exercises.
Brzycki Formula
1RM = Weight × (36 ÷ (37 - Reps))Tends to give more conservative estimates, especially for higher rep ranges. Often used in academic and research settings.
Other Formulas
- Lander: Good for moderate rep ranges (6-10 reps)
- Lombardi: Works well for lower rep ranges (1-5 reps)
- Mayhew: Designed for untrained individuals
- O'Conner: Conservative formula emphasizing safety
- Wathan: Better for higher repetition ranges
Training Load Percentages
Percentage-Based Training
Once you know your 1RM, you can calculate appropriate training loads for different goals:
Warm-up, form work, muscular endurance, and recovery sessions.
Hypertrophy (muscle growth), muscular endurance, and technique refinement.
Hypertrophy and strength development, most common training range.
Strength development, power training, and competition preparation.
Maximum strength, peaking for competition, and neural adaptations.
Factors Affecting Accuracy
Training Experience
- Beginners: May have less accurate estimates due to poor rep-max relationships
- Intermediate: Generally have the most accurate estimates
- Advanced: May require exercise-specific formulas for best accuracy
Exercise-Specific Factors
- Compound Movements: More accurate estimates (bench, squat, deadlift)
- Isolation Exercises: Less reliable estimates due to different fatigue patterns
- Muscle Group Size: Larger muscle groups tend to have more accurate estimates
Individual Factors
- Fiber Type: Fast-twitch dominant individuals may exceed estimates
- Training Background: Powerlifting background improves accuracy
- Fatigue State: Rest, nutrition, and recovery affect actual performance
Practical Applications
Program Design
- Set appropriate training loads for different phases
- Progress systematically by increasing percentages
- Avoid overtraining by staying within appropriate ranges
- Plan deload weeks using lower percentages
Progress Tracking
- Test estimated 1RM every 4-6 weeks
- Look for consistent improvement over time
- Compare strength across different exercises
- Adjust training if progress stalls
Competition Preparation
- Use estimates to plan opening attempts
- Conservative second attempts around 100-103%
- Aggressive third attempts around 105-110%
- Account for competition environment and timing
Safety Considerations
- Never attempt true 1RM without proper supervision and safety equipment
- Always warm up thoroughly: Start with bodyweight, then 50%, 70%, 85%, 95%
- Use spotters: Essential for bench press, squat, and overhead movements
- Know your limits: Estimation is safer than testing for most people
- Listen to your body: Don't attempt max efforts when fatigued or injured