One Rep Max Calculator
Calculate your estimated one rep max (1RM) based on the weight you lift and the number of repetitions performed.
1RM Formulas
Epley Formula
Brzycki Formula
What is One Rep Max (1RM)?
One Rep Max (1RM) is the maximum weight you can lift for a single repetition with proper form. It's the gold standard for measuring strength and a foundation for designing effective training programs.
While you can test your actual 1RM by attempting a maximal lift, this calculator uses established formulas to estimate your 1RM from submaximal efforts—safer and often more practical for training purposes.
Strength Benchmark
1RM provides a standardized way to measure and track strength progress over time.
Training Prescription
Training percentages are based on 1RM: 70% for hypertrophy, 85% for strength, etc.
Goal Setting
Knowing your 1RM helps set realistic strength goals and track progress.
Relative Strength
Compare strength across body weights and genders using 1RM ratios.
Understanding 1RM Formulas
Multiple formulas exist to estimate 1RM from submaximal lifts. Each has different characteristics:
Epley Formula
1RM = Weight × (1 + Reps/30). Simple and widely used. Tends to be accurate for moderate rep ranges (5-10). May overestimate for high reps.
Brzycki Formula
1RM = Weight / (1.0278 - 0.0278 × Reps). Very accurate for 1-10 reps. Becomes unreliable above 10 reps. Popular in strength sports.
Lander Formula
1RM = Weight / (1.013 - 0.0267 × Reps). Similar accuracy to Brzycki. Some prefer it for lower rep ranges (1-6).
Why Average?
Different formulas have different biases. Averaging multiple formulas often gives the most reliable estimate across different rep ranges and lifters.
Training Percentages
Once you know your 1RM, you can calculate appropriate training weights for different goals:
| % of 1RM | Reps | Primary Adaptation | Rest Period |
|---|---|---|---|
| 90-100% | 1-3 | Maximal Strength / Neural | 3-5+ min |
| 80-90% | 3-6 | Strength / Some Hypertrophy | 2-4 min |
| 70-80% | 6-12 | Hypertrophy / Strength | 1-2 min |
| 60-70% | 12-20 | Muscular Endurance | 30-90 sec |
| < 60% | 20+ | Endurance / Warm-up | 30 sec |
How to Use Your 1RM
Your 1RM is a tool for programming, not just a number to chase. Here's how to apply it effectively:
Periodization
Vary intensity throughout training cycles. Start at 70-75% for volume blocks, progress to 85-95% for peaking phases. This prevents plateaus and overtraining.
Progressive Overload
When you can hit the target reps at a percentage, your 1RM has increased. Recalculate and adjust weights accordingly.
RPE Adjustment
Percentages are starting points. Adjust based on daily readiness. If 80% feels like a 9 RPE (should be ~7), your true 1RM may be lower today.
Exercise Specificity
1RM is lift-specific. Your squat 1RM doesn't predict your deadlift 1RM. Calculate separately for each major lift.
Testing Your Actual 1RM
While calculators are useful, you may want to test actual 1RM for competition preparation or personal records:
Proper Warm-up
Start with general warm-up (5-10 min cardio). Then progressive sets: empty bar × 10, 50% × 5, 70% × 3, 80% × 2, 90% × 1, then attempt 1RM.
Be Fresh
Test after 2-3 days of rest. Avoid testing at the end of a hard training week. Fatigue masks true strength.
Use Spotters
Always have competent spotters for bench press and squat. Use safety bars in a rack. Never max out alone.
Record Attempts
Video your lifts to assess form. A grind rep with form breakdown may not count in competition. True 1RM should be clean.
Smart Jumps
Make 2-3 attempts max. Jump 2.5-5% between attempts. Don't burn out with too many near-maximal attempts.
Strength Standards
How strong is strong? These general standards help contextualize your lifts (values shown are 1RM relative to body weight):
Squat (Back Squat)
Beginner: 0.75× BW | Intermediate: 1.25× BW | Advanced: 1.75× BW | Elite: 2.5× BW
Bench Press
Beginner: 0.5× BW | Intermediate: 1× BW | Advanced: 1.5× BW | Elite: 2× BW
Deadlift
Beginner: 1× BW | Intermediate: 1.5× BW | Advanced: 2× BW | Elite: 3× BW
Overhead Press
Beginner: 0.35× BW | Intermediate: 0.65× BW | Advanced: 1× BW | Elite: 1.35× BW
Limitations of 1RM Estimates
While useful, 1RM calculators have limitations to understand:
Rep Range Accuracy
Formulas are most accurate between 1-10 reps. Above 10 reps, accuracy decreases significantly. A set of 20 won't predict 1RM well.
Exercise Variation
Formulas are developed primarily for compound lifts. Isolation exercises and machines may not follow the same rep-to-1RM relationship.
Individual Variation
Some people are 'high rep' or 'low rep' responders. Your actual 1RM may be higher or lower than calculated based on your fiber type.
Technique Under Load
1RM requires different technique than submaximal work. Speed, bracing, and mental approach differ. Calculated 1RM assumes perfect transfer.
Frequently Asked Questions
Which 1RM formula is most accurate?
No single formula is universally best. Brzycki and Epley are most popular and generally accurate for 1-10 reps. The 'Average' option in this calculator combines multiple formulas for improved reliability across different scenarios.
How often should I retest my 1RM?
Recalculate every 4-8 weeks as strength changes. Actual testing should be less frequent—every 8-12 weeks or before competitions. Regular maxing out increases injury risk and doesn't improve strength.
Why is my actual 1RM different from calculated?
Several factors affect this: your ratio of slow-twitch to fast-twitch muscle fibers, technique efficiency at maximal loads, psychological readiness, and fatigue level. Calculations are estimates, not guarantees.
Should I train to failure to get accurate 1RM estimates?
Not necessarily. Leaving 1-2 reps in reserve (RIR) gives nearly as accurate estimates while reducing injury risk and fatigue. Training to failure regularly can impair recovery.
Can I use 1RM calculators for all exercises?
They work best for compound barbell movements (squat, bench, deadlift, press). Machine exercises and isolation movements don't follow the same rep-to-max relationship. Use these estimates cautiously for non-compound lifts.
Is a higher rep set or lower rep set more accurate?
Lower rep sets (3-6 reps) typically give more accurate 1RM estimates. As reps increase beyond 10, accuracy decreases due to endurance factors influencing performance more than pure strength.
What's the difference between 1RM and e1RM?
1RM is your actual tested one-rep maximum. e1RM (estimated 1RM) is calculated from submaximal lifts. Programs may refer to either. When in doubt, use e1RM from recent training data rather than an old tested 1RM.
How do I know if I should increase my estimated 1RM?
When your performance at a given percentage exceeds expectations (e.g., hitting 8 reps at what should be your 5-rep weight), your 1RM has likely increased. Recalculate using your new performance data.
Pro Tips
- Bookmark this calculator for quick access in the future
- Use the share button to send your results to others
- Try different scenarios to compare outcomes
- Check out our related calculators for more insights
Found this calculator helpful? Share it with others: