Calculate your estimated one-rep maximum (1RM) for any lift using multiple scientifically-validated formulas and get personalized training percentages
Enter your details and click calculate to see your estimated one-rep maximum
One Rep Max (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise while maintaining proper form. It represents the peak force your muscles can generate in an all-out effort and serves as a crucial measure of absolute strength. Your 1RM differs for each exercise—your bench press 1RM won't be the same as your squat or deadlift 1RM.
Knowing your 1RM is valuable for designing effective training programs, tracking strength progress over time, setting realistic goals, and ensuring you're training at appropriate intensities for your objectives. Rather than testing your actual 1RM frequently (which is taxing and carries injury risk), you can estimate it accurately using submaximal loads—lifting a weight you can perform for multiple reps and using validated formulas to calculate your estimated 1RM.
Program Design: Once you know your 1RM, you can calculate training percentages for different goals. Lifting at 70-80% of your 1RM targets hypertrophy (muscle growth), while 85-95% focuses on strength development. Without knowing your 1RM, you're essentially training blind, unable to apply progressive overload systematically.
Progress Tracking: Your 1RM provides a quantitative measure of strength that you can track over weeks, months, and years. Seeing your 1RM increase over time provides concrete evidence of progress, helping maintain motivation and allowing you to adjust your program when progress stalls.
Safety and Efficiency: Estimating your 1RM through submaximal lifts is safer than regularly testing maximum efforts. You can train effectively at appropriate intensities without the fatigue, joint stress, and injury risk associated with frequent maximal attempts.
This calculator uses three validated formulas:
Epley Formula: 1RM = Weight × (1 + Reps/30) - Most popular and accurate for 1-10 reps
Brzycki Formula: 1RM = Weight × (36 / (37 - Reps)) - Slightly more conservative
Lombardi Formula: 1RM = Weight × Reps^0.1 - Alternative calculation method
For best accuracy, use weights you can lift for 3-10 reps. Estimates become less accurate above 12 reps or at 1-2 reps.
Different percentages of your 1RM target different training adaptations. Use these guidelines to structure your workouts based on your goals:
| % of 1RM | Reps | Sets | Training Goal |
|---|---|---|---|
| 50-60% | 12-20+ | 3-4 | Muscular endurance, technique practice, warmup |
| 60-70% | 10-15 | 3-5 | Muscular endurance, metabolic conditioning |
| 70-80% | 7-12 | 3-5 | Hypertrophy (muscle growth), balanced development |
| 80-85% | 5-8 | 3-5 | Strength-hypertrophy combination |
| 85-90% | 3-5 | 3-5 | Maximum strength development |
| 90-95% | 2-3 | 2-4 | Peak strength, powerlifting specific |
| 95-100% | 1-2 | 1-3 | Maximal strength testing, competition prep |
These ranges provide general guidelines—individual responses vary. Beginners should focus primarily on 70-85% of 1RM for balanced strength and hypertrophy development. Advanced lifters incorporate all intensity zones through periodization.
Example: Bench Press with 100kg 1RM
This approach ensures you're training at appropriate intensities for different adaptations throughout the week, applying progressive overload systematically rather than guessing weights randomly.
Test or re-estimate your 1RM every 4-8 weeks to track progress and adjust training weights. Avoid testing too frequently—it's taxing on your nervous system and joints. Instead, estimate 1RM using submaximal lifts regularly, saving actual 1RM attempts for competitions or specific testing phases.
If you choose to test your actual 1RM rather than estimate it:
Testing true 1RM carries inherent risks including muscle strains, joint stress, and potential injury. Beginners with less than 1 year of training experience should avoid 1RM testing entirely, instead using estimated 1RM from submaximal lifts. Even experienced lifters should test 1RM sparingly—perhaps only when peaking for competition. The physical and mental stress of maximal attempts can take days or weeks to recover from, potentially disrupting your training program.
Progressive Overload: Consistently increase training stress over time through added weight, reps, or sets. Your 1RM won't improve without progressively challenging your muscles beyond their current capacity.
Vary Intensity: Include training across multiple intensity zones—heavy (85-90%), moderate (75-80%), and light (60-70%). Each zone provides different stimuli contributing to overall strength development.
Technical Proficiency: Perfect your form on each lift. Technical improvements allow you to express existing strength more efficiently, often adding 5-10% to your 1RM without gaining actual strength.
Adequate Recovery: Strength gains occur during recovery, not training. Sleep 7-9 hours nightly, manage stress, eat sufficient calories and protein, and include deload weeks every 4-6 weeks.
Patience: Strength development is slow. Expect 1RM increases of 2.5-5kg monthly on upper body lifts and 5-10kg monthly on lower body lifts for beginners. Progress slows significantly with training experience.
How accurate are 1RM estimates? For lifts performed with 3-10 reps, estimates are typically within 5-10% of actual 1RM. Accuracy decreases outside this range—very high reps (15+) or very low reps (1-2) produce less reliable estimates.
Can I use my 1RM from one exercise for others? No. Each exercise has its own 1RM based on the specific muscles involved, leverage, and movement pattern. Your squat 1RM provides no information about your bench press 1RM.
Should I train to failure? No. Training to failure frequently increases injury risk and impairs recovery. Leave 1-2 reps "in the tank" on most sets, only approaching failure occasionally on final sets of isolation exercises.
How often should I update my estimated 1RM? Re-calculate every 4-6 weeks as your strength improves. Your training percentages should reflect your current strength levels, not where you were months ago.
What if my 1RM isn't increasing? Strength plateaus are normal. Assess your program (volume, intensity, frequency), ensure adequate recovery (sleep, nutrition, stress), and consider deloading or changing exercise variations to stimulate new adaptations.