One Rep Max (1RM) Calculator
This one rep max calculator estimates the maximum weight you can lift for a single repetition based on your submaximal lift data. Enter the weight and reps performed to calculate your 1RM using multiple validated formulas including Epley and Brzycki.
One Rep Max Calculator
Estimate your 1RM from a submaximal set using several proven formulas.
Use a set between 2 and 30 reps for the best estimate.
Frequently Asked Questions
What is a one rep max (1RM)?
A one rep max (1RM) is the maximum amount of weight you can lift for a single repetition with proper form. It is the gold standard for measuring absolute strength in a given exercise and is used to program training loads, track progress, and compare strength levels between individuals. Rather than testing a dangerous true max, most lifters use submaximal prediction formulas to estimate their 1RM safely.
What is the most accurate 1RM formula?
The most accurate 1RM formula depends on the rep range used. The Epley formula (1RM = Weight x (1 + Reps/30)) tends to be more accurate for higher rep ranges of 6-10 reps, while the Brzycki formula (1RM = Weight x 36 / (37 - Reps)) is more accurate for lower rep ranges of 1-5 reps. For the best overall estimate, use multiple formulas and average the results, which is exactly what this calculator does.
How do you calculate 1RM without maxing out?
You can calculate your 1RM without maxing out by using submaximal testing. Perform a set with a weight you can lift for 3-10 reps with good form, then apply a prediction formula like Epley or Brzycki. For example, if you bench press 185 lbs for 5 reps, the Epley formula estimates your 1RM as 185 x (1 + 5/30) = 216 lbs. This method is safer than attempting a true one-rep max and provides a reliable estimate for programming.
What percentage of 1RM should I train at?
Training percentages depend on your goal. For maximum strength, train at 85-100% of 1RM for 1-3 reps. For strength and power, use 80-85% for 4-6 reps. For muscle hypertrophy (growth), use 67-85% for 6-12 reps. For muscular endurance, use 50-67% for 12-20+ reps. Most periodized programs cycle through these zones over weeks or months to develop well-rounded fitness.
How often should I test my 1RM?
Intermediate lifters should retest their estimated 1RM every 4-8 weeks to keep training loads current. Beginners should test every 8-12 weeks since their strength gains come quickly but stabilize between tests. Advanced lifters may test every 8-12 weeks aligned with peaking cycles. Using a submaximal calculator test (lifting for 3-5 reps) is safer and can be done more frequently than attempting a true one-rep max.
Is testing 1RM dangerous?
Attempting a true one-rep max can be risky without proper form, adequate warm-up, and a competent spotter. The risk of injury increases significantly when lifting near maximal loads with poor technique or fatigue. Submaximal 1RM prediction using a calculator is much safer — you lift a manageable weight for multiple reps and let the math estimate your max. This approach is recommended for most recreational lifters and beginners.
What is the Epley formula?
The Epley formula is 1RM = Weight x (1 + Reps / 30). Developed by Boyd Epley, it is one of the most widely cited one rep max prediction equations and is used by the National Strength and Conditioning Association (NSCA). For example, if you lift 200 lbs for 5 reps, your estimated 1RM is 200 x (1 + 5/30) = 233 lbs. The Epley formula tends to be most accurate in the 6-10 rep range.
What is the Brzycki formula?
The Brzycki formula is 1RM = Weight x (36 / (37 - Reps)). Created by Matt Brzycki, this formula is particularly accurate for lower rep ranges (1-5 reps) and is commonly used in collegiate strength programs. For example, if you lift 200 lbs for 5 reps, the Brzycki formula estimates your 1RM as 200 x (36 / 32) = 225 lbs. It produces nearly identical results to the Epley formula at 10 reps.
What are good strength standards for bench press?
Bench press strength standards vary by experience level relative to bodyweight. A novice lifter (less than 1 year training) typically benches about 0.5x bodyweight. An intermediate lifter (1-3 years) benches around 1x bodyweight. An advanced lifter (3-5+ years) benches approximately 1.5x bodyweight. Elite and competitive lifters may bench 2x bodyweight or more. These standards vary by age, sex, and body composition.
Does 1RM differ by exercise?
Yes, your one rep max varies significantly by exercise because different movements use different muscle groups and leverage patterns. Compound lower-body exercises like squats and deadlifts typically produce the highest 1RM values because they engage the largest muscles. Upper-body exercises like bench press produce moderate values, while isolation exercises like overhead press or curls have the lowest 1RM. You should calculate and track 1RM separately for each exercise.
How to Calculate Your One Rep Max (1RM)
What is a One Rep Max (1RM)?
A one-rep max (1RM) is the maximum amount of weight you can lift for a single repetition of a given exercise with proper form. It is widely considered the gold standard for measuring absolute strength in weight training and powerlifting.
Rather than attempting a true 1RM in the gym, which carries a higher risk of injury, lifters commonly use submaximal loads and rep counts to estimate their 1RM mathematically. This approach is safer and can be just as accurate for programming purposes. Our 1RM prediction calculator uses seven validated formulas to give you the most reliable estimate possible.
How to Use This Calculator
- Enter the weight you lifted in pounds (lbs) or kilograms (kg) using the unit toggle.
- Enter the number of reps you completed (between 2 and 30). If you lifted for only 1 rep, the weight itself is your 1RM.
- Click "Calculate 1RM" to see your estimated one-rep max from multiple different formulas.
- Review the formula breakdown and the percentage-based training weight table to plan your workouts.
For the most accurate 1RM prediction, use a weight that allows you to complete between 2 and 10 reps with good form. Estimates become less reliable beyond 10 reps.
1RM Formulas Explained
This calculator uses multiple well-established formulas from exercise science research. Each formula takes your weight and reps as input and produces a slightly different estimate. The calculator averages all results to give you a reliable overall 1RM prediction.
Epley Formula (Most Popular)
1RM = weight x (1 + reps / 30)
Developed by Boyd Epley, this is the most widely cited 1RM prediction equation and is used by the National Strength and Conditioning Association (NSCA). Best for rep ranges of 6-10.
Brzycki Formula
1RM = weight x 36 / (37 - reps)
Created by Matt Brzycki, this formula is particularly accurate for lower rep ranges (1-5 reps) and is commonly used in collegiate strength programs. Produces nearly identical results to Epley at 10 reps.
Lombardi Formula
1RM = weight x reps^0.10
A power-based formula that tends to produce slightly more conservative estimates compared to Epley and Brzycki. Works well across a broad range of reps.
Mayhew Formula
1RM = (100 x weight) / (52.2 + 41.9 x e^(-0.055 x reps))
Uses an exponential decay model. This formula was originally derived from bench press data and works well across a wide rep range.
O'Conner Formula
1RM = weight x (1 + 0.025 x reps)
A simple linear model that provides a quick estimate. It tends to produce lower predictions for higher rep ranges compared to other formulas.
Wathan Formula
1RM = (100 x weight) / (48.8 + 53.8 x e^(-0.075 x reps))
Developed for a wide range of exercises, the Wathan formula uses an exponential model and is considered one of the most accurate for moderate rep ranges (5-10).
Lander Formula
1RM = (100 x weight) / (101.3 - 2.67123 x reps)
A linear regression-based formula that provides reliable estimates for rep ranges of 2-12. It is straightforward and produces results between Epley and Brzycki.
Formula Comparison Table
Each 1RM formula has strengths in different scenarios. Use this comparison to understand which formula best fits your training:
| Formula | Best For | Equation |
|---|---|---|
| Epley | 6-10 reps, general use | W x (1 + R/30) |
| Brzycki | 1-5 reps, low rep sets | W x 36 / (37 - R) |
| Lombardi | Broad rep range, conservative | W x R^0.10 |
| Mayhew | Bench press, wide rep range | 100W / (52.2 + 41.9e^(-0.055R)) |
| O'Conner | Quick estimate, low reps | W x (1 + 0.025R) |
| Wathan | 5-10 reps, high accuracy | 100W / (48.8 + 53.8e^(-0.075R)) |
| Lander | 2-12 reps, balanced | 100W / (101.3 - 2.67123R) |
W = weight lifted, R = reps completed. For the most reliable 1RM prediction, average all formulas as this calculator does.
Examples
Example 1: Bench Press
You bench press 185 lbs for 5 reps.
- Epley: 185 x (1 + 5/30) = 215.8 lbs
- Brzycki: 185 x 36 / (37 - 5) = 208.1 lbs
- Lombardi: 185 x 5^0.10 = 216.2 lbs
- Average across all formulas: approximately 210 lbs
Example 2: Squat
You squat 100 kg for 8 reps.
- Epley: 100 x (1 + 8/30) = 126.7 kg
- Brzycki: 100 x 36 / (37 - 8) = 124.1 kg
- O'Conner: 100 x (1 + 0.025 x 8) = 120.0 kg
- Average across all formulas: approximately 123.75 kg
Example 3: Deadlift
You deadlift 315 lbs for 3 reps.
- Epley: 315 x (1 + 3/30) = 346.5 lbs
- Brzycki: 315 x 36 / (37 - 3) = 333.5 lbs
- O'Conner: 315 x (1 + 0.025 x 3) = 338.6 lbs
- Average across all formulas: approximately 340 lbs
Training Percentage Chart
Once you know your estimated 1RM, use this percentage-based training chart to structure your workouts. Different percentages of your 1RM correspond to different training goals and rep ranges:
| % of 1RM | Reps | Training Goal |
|---|---|---|
| 100% | 1 | Max Strength (peaking / competition) |
| 95% | 2 | Strength (neural adaptations) |
| 90% | 3-4 | Strength (heavy training) |
| 85% | 5 | Strength / Hypertrophy |
| 80% | 6-8 | Hypertrophy (muscle growth) |
| 75% | 8-10 | Hypertrophy (volume) |
| 70% | 10-12 | Hypertrophy / Endurance |
| 65% | 12-15 | Endurance (metabolic stress) |
| 60% | 15-20 | Endurance (conditioning) |
The training weight table in the calculator automatically rounds weights to the nearest 2.5 lbs or 1.25 kg so you can load a barbell with standard plates.
Strength Standards by Exercise
These general strength standards are expressed as a multiple of bodyweight for adult male lifters. Female standards are typically 60-70% of these values. Use your estimated 1RM to see where you stand:
| Exercise | Novice | Intermediate | Advanced | Elite |
|---|---|---|---|---|
| Bench Press | 0.5x BW | 1.0x BW | 1.5x BW | 2.0x BW |
| Squat | 0.75x BW | 1.25x BW | 2.0x BW | 2.5x BW |
| Deadlift | 1.0x BW | 1.5x BW | 2.25x BW | 3.0x BW |
| Overhead Press | 0.35x BW | 0.65x BW | 1.0x BW | 1.35x BW |
BW = bodyweight. Standards are approximate and vary by age, training history, and body composition. Novice: <1 year, Intermediate: 1-3 years, Advanced: 3-5+ years, Elite: competitive level.
Use Cases
Strength Program Design
Coaches and athletes use 1RM estimates to prescribe training loads. Programs like Wendler 5/3/1, Starting Strength, and Juggernaut Method all rely on percentage-based programming derived from a 1RM.
Progress Tracking
By periodically recalculating your estimated 1RM, you can track strength gains over time without needing to test a true max every training cycle.
Competition Preparation
Powerlifters and weightlifters use 1RM estimates to plan their attempt selections for competition, ensuring they open at a manageable weight and build toward a personal record.
Rehabilitation and Return to Training
After an injury, a 1RM calculator helps determine safe working weights based on submaximal tests, allowing a gradual and controlled return to full training loads.
Tips and Best Practices
- Use a rep range of 2-10 for the most accurate estimate. Higher rep sets (15+) reduce prediction accuracy.
- Perform your test set with strict form and full range of motion for reliable results.
- Warm up properly before your test set to ensure peak performance without fatigue.
- Retest your estimated 1RM every 4-8 weeks to keep your training weights current.
- Remember that 1RM estimates are exercise-specific. A squat 1RM does not predict your deadlift 1RM.
- Consider averaging multiple formulas (as this calculator does) rather than relying on a single equation for a more robust estimate.
- Never attempt a true 1RM without a spotter or safety equipment in place.