One Rep Max Calculator
Estimate your one-rep max using 7 proven formulas. Enter the weight you lifted and how many reps you completed to get your estimated 1RM.
Enter a weight and number of reps to calculate your estimated one rep max.
How to Use This Calculator
To estimate your one rep max, enter the weight you successfully lifted and the number of reps you completed. The calculator works best with recent sets where you pushed close to failure (RPE 8-10). For most accurate results, use a weight you can lift for 3-10 reps.
The calculator instantly shows your estimated 1RM from seven different formulas, plus the average of all formulas as our recommended estimate. Below that, you'll see a percentage chart showing suggested working weights for different rep ranges.
Understanding the Formulas
Each 1RM formula was developed from research on lifter performance and uses slightly different mathematical models:
Epley
One of the oldest and most tested formulas. Tends to be most accurate for sets of 10+ reps.
Brzycki
The most commonly used formula in strength training. Reliable across most rep ranges and the default in many training apps.
Lombardi
Uses a simple power function. Can underestimate for very low or very high rep ranges.
Mayhew
Developed from regression analysis of actual lifter data. Validated in peer-reviewed research.
O'Conner
More conservative estimate. Good for lifters who want a safe starting point for percentage-based training.
Wathan
Performs well for lower rep ranges (1-5). Often used for powerlifting estimates.
Because individual differences affect which formula is most accurate for you, we recommend using the average of all formulas as your working estimate.
When to Test Your 1RM vs. Estimate It
Actually testing your one rep max — loading the bar to a weight you can only lift once — carries real risk. Form breakdown at maximal loads can cause injury, especially on exercises like squats, deadlifts, and bench press.
For most training purposes, estimating your 1RM is both safer and sufficient.
Use Estimates For
- Programming training percentages
- Tracking strength progress over time
- Comparing performance across rep ranges
Test Your Actual 1RM If
- Preparing for a powerlifting competition
- Want a definitive post-program benchmark
- Have specific max strength goals
If you do test, prepare properly: take a full deload week beforehand, warm up thoroughly with progressive sets, have a qualified spotter for any lift that could pin you, and only attempt a true max when fully recovered.
How to Use Your 1RM for Programming
Your estimated 1RM enables percentage-based training, where working weights are calculated as percentages of your max. This is common in programs like 5/3/1, Juggernaut Method, and many periodization schemes.
The percentage chart above shows typical training zones:
Maximal Strength
High neural demand, minimal volume.
Strength-Focused
Heavy loads, moderate volume.
Hypertrophy
Moderate loads, higher volume.
Endurance
Lighter loads, high volume.
An alternative approach — and the one we use at MySetPlan — is RPE (Rate of Perceived Exertion) based training. Instead of calculating exact percentages, you select weights based on how hard the set feels. This auto-regulates to your daily readiness and doesn't require recalculating maxes. Learn more in our evidence-based training principles guide.
Frequently Asked Questions
How accurate is a 1RM calculator?
One rep max calculators are generally accurate within 5-10% for rep ranges of 1-10. Accuracy decreases as rep count increases beyond 10, and results can vary based on exercise type, technique, and individual factors like muscle fiber composition and training experience. For the most accurate estimate, use a weight you can lift for 5 or fewer reps.
Which 1RM formula is most accurate?
No single formula is universally most accurate. Brzycki is the most commonly used and works well for most lifters. Epley tends to be more accurate for higher rep ranges (10+), while Wathan performs better for lower rep ranges (under 5). Our recommended approach is to use the average of all formulas, which accounts for individual variation.
Should I actually test my one rep max?
Testing a true 1RM carries injury risk and requires proper preparation, including warm-up sets, a spotter for compound lifts, and ideally peak freshness (not after a hard training block). For most training purposes, estimating your 1RM from a 3-5 rep max is safer and equally effective for programming percentages. Save true max testing for competition or occasional benchmarks.
How often should I recalculate my 1RM?
Recalculate your 1RM every 4-8 weeks, or whenever you notice significant strength changes. If your training uses percentage-based programming, updating your estimated max ensures your working weights remain appropriate. Many lifters update their 1RM at the end of each training block or mesocycle.
What's a good 1RM for bench press, squat, or deadlift?
Strength standards vary significantly based on bodyweight, sex, training age, and goals. As rough benchmarks for intermediate male lifters: bodyweight bench press, 1.5x bodyweight squat, and 2x bodyweight deadlift are solid goals. For women, multiply these by approximately 0.7. However, comparing yourself to your own progress over time is more valuable than external standards.
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