1RM Calculator
Estimate your one-rep max for bench press, squat, deadlift, and 15+ exercises using 7 scientific formulas
1RM Calculator
Estimate your one-rep max instantly
Your results
Updated instantlyEstimated 1RM for Bench Press
Tip: Re-calculate with a heavier or lighter set to see how your 1RM range changes.
Training Load Chart Percent of 1RM
Suggested Warmup Sets Before top set
| Set | %1RM | Weight | Reps |
|---|
This 1RM calculator uses seven validated scientific formulas to estimate your one-rep max with precision. Simply enter the weight you lifted and how many reps you completed—our algorithm averages results from Epley, Brzycki, Lombardi, Mayhew, O'Conner, Wathan, and Lander formulas to minimize single-formula bias.
Whether you're calculating your bench press 1RM, squat max, or deadlift potential, you'll get instant results plus a complete training load chart showing optimal weights for every rep range from 55% to 100% of your max.
How the 1RM Calculator Works
Epley Formula
The most widely used formula. Simple, reliable, and accurate for 1-10 rep ranges. Developed by Boyd Epley at the University of Nebraska.
Brzycki Formula
Created by Matt Brzycki. Tends to give slightly conservative estimates, which many coaches prefer for safety. Best for 1-6 reps.
Mayhew Formula
Research-based exponential formula. Maintains accuracy across wider rep ranges, particularly useful for 8-12 rep estimates.
Wathan Formula
Another exponential model that provides stable estimates. Often produces results between Epley and Brzycki.
💡 The Clickzy Accuracy Stack™
Rather than relying on a single formula, our calculator averages all seven validated methods. This multi-formula approach reduces estimation error by canceling out the biases inherent in each individual equation—giving you the most reliable 1RM estimate possible.
What Most 1RM Calculators Don't Tell You
All formulas assume you trained to failure
If you stopped with 2-3 reps in reserve, your actual 1RM is higher than the calculator shows. That's why we include RPE adjustment—it accounts for effort level and gives a more accurate estimate.
Accuracy drops significantly after 10 reps
The mathematical relationship between submaximal weights and your true 1RM becomes increasingly unpredictable beyond 10 repetitions. For best results, use data from 3-8 rep sets.
Your 1RM varies by exercise—and by day
A bench press 1RM calculated from 5 reps won't transfer perfectly to deadlift estimates. Different lifts have different strength curves. Sleep, nutrition, stress, and even time of day affect your true max by 5-10%.
Technical breakdown affects estimates
If your form degrades on rep 4 of a 5-rep set, you're not getting an accurate input for the calculator. Only count reps performed with consistent, quality technique for reliable 1RM estimates.
How to Use Your 1RM Results
Strength Programs
Programs like 5/3/1, Starting Strength, and Texas Method prescribe weights as percentages of 1RM. Use the chart to find exact weights for each training day.
- Heavy singles: 90-100%
- Strength sets: 80-90%
- Volume work: 65-80%
Hypertrophy Training
For muscle building, most research shows 60-80% of 1RM is optimal. Our percentage chart helps you dial in the right weight for 8-15 rep sets.
- Growth zone: 65-80%
- Metabolic stress: 55-65%
- Drop sets: 40-60%
Progress Tracking
Track your estimated 1RM over weeks and months to measure strength gains without frequent max-out sessions that risk injury.
- Test every 4-6 weeks
- Use same rep range
- Log conditions
Frequently Asked Questions
Everything you need to know about 1RM calculations and training applications
Your 1RM is the maximum amount of weight you can lift for a single repetition with proper form. It's a key metric for measuring strength, programming training loads, and tracking progress over time. Most strength programs base their percentages on your estimated or tested 1RM.
This calculator uses 7 validated formulas (Epley, Brzycki, Lombardi, Mayhew, O'Conner, Wathan, and Lander) and averages them for optimal accuracy. For rep ranges of 1-10, accuracy is typically within 5% of your true max. Accuracy decreases with higher rep ranges (10+) as the relationship becomes less linear.
The Epley and Brzycki formulas are considered most accurate for rep ranges of 1-10. Brzycki tends to give slightly lower estimates and works best for 1-6 reps. For higher rep ranges (10+), the Mayhew formula often provides better estimates. Our calculator averages all formulas to minimize individual formula bias.
Yes, the calculator works for compound lifts like bench press, squat, deadlift, and overhead press. It's less accurate for isolation exercises and machine movements. For Olympic lifts (clean, snatch, jerk), technique plays a larger role, so estimates may be less reliable.
RPE (Rate of Perceived Exertion) measures how hard a set felt on a scale of 6-10. RPE 10 means you couldn't do another rep; RPE 8 means you had 2 reps left. Using RPE gives a more accurate 1RM estimate by accounting for your actual effort level rather than assuming every set is to failure.
For most lifters, re-estimating your 1RM every 4-8 weeks provides useful data for program adjustments. Actual max testing should be done sparingly (every 8-12 weeks) as it's fatiguing and carries injury risk. Regular sub-maximal tests using this calculator are safer and nearly as accurate.
The relationship between reps and maximum weight isn't perfectly linear. Lower rep ranges (1-5) have a more predictable relationship to your 1RM. As reps increase, factors like muscular endurance, technique breakdown, and mental fatigue become more significant, making predictions less accurate.
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