One Rep Max Calculator
1RM Estimate · 7 Formulas · Training %
lbs
The weight you lifted for the set below
reps
1 to 30 reps. Most accurate for 1 to 10 reps.
Enter the weight lifted and reps completed to estimate your one rep max.
1RM Estimate (Epley)
0
lbs estimated max
All Formula Estimates
Training Percentages
How 1RM Formulas Work
With the Epley formula, 225 lb for 5 reps estimates a one rep max of about 262.5 lb: weight × (1 + reps ÷ 30). Brzycki, the other common formula, gives 253 lb for the same set. Enter the weight and reps of a hard set above to see all seven formulas side by side and a training table built from your 1RM.
One Rep Max (1RM) is the maximum weight you can lift for a single repetition with proper form. Directly testing your 1RM carries injury risk, especially for inexperienced lifters. Predictive formulas allow you to estimate 1RM from a submaximal set, typically using a weight you can lift for 2-10 reps with full effort.
All 1RM formulas use the same two variables: the weight lifted and the number of reps completed. They differ in their mathematical models and the populations they were validated on. The Epley formula (1985) is the most widely used. Brzycki is preferred by some coaches for sets in the 2-10 rep range. Most formulas become increasingly inaccurate above 10 reps due to the growing influence of muscular endurance vs pure strength.
| Formula | Year | Equation (w = weight, r = reps) | Notes |
|---|---|---|---|
| Epley | 1985 | w × (1 + r/30) | Most widely cited |
| Brzycki | 1993 | w × 36 / (37 − r) | Preferred for 2 to 10 reps |
| Lander | 1985 | 100w / (101.3 − 2.67123 × r) | Good general accuracy |
| Lombardi | 1989 | w × r0.10 | Tends to overestimate slightly |
| Mayhew et al. | 1992 | 100w / (52.2 + 41.9 × e−0.055r) | Validated on college athletes |
| O'Conner et al. | 1989 | w × (1 + 0.025r) | Conservative estimate |
| Wathan | 1994 | 100w / (48.8 + 53.8 × e−0.075r) | Similar to Mayhew |
Most Accurate Rep Range
All formulas are most accurate for sets of 2 to 6 reps. Accuracy degrades significantly above 10 reps because endurance becomes a larger factor. For best 1RM estimation, perform a set of 3 to 5 reps with a weight that represents a true maximum effort for that rep count. Avoid predicting 1RM from sets of 15+ reps.
How to Use Training Percentages
Training zones by % of 1RM: 90-100% = max effort, 1-3 reps (strength/peaking). 80-90% = heavy, 3-5 reps (strength). 70-80% = moderate, 5-8 reps (hypertrophy/strength). 60-70% = light, 8-15 reps (hypertrophy/endurance). Below 60% = technique work and conditioning.
1RM vs Rep Max
Different rep maxes (RM): 1RM = 100%. 3RM ≈ 93%. 5RM ≈ 87%. 8RM ≈ 80%. 10RM ≈ 75%. 12RM ≈ 70%. 15RM ≈ 65%. These percentages are averages; individual fast-twitch/slow-twitch muscle fiber ratios cause significant person-to-person variation. Some people rep out 1RM at 10 reps; others fatigue faster.
Why Formulas Differ
Each formula was validated on a different population (athletes vs untrained, specific sports, age groups, specific lifts). No formula is universally "best." Use the average of multiple formulas for the most robust estimate. The spread between formulas on the same input data tells you your confidence interval: if they all agree within 5 lbs, the estimate is reliable.
Reps vs Percentage of 1RM: What the Formulas Say
The share of your one rep max you can lift for a given number of reps, according to three of the formulas. Computed directly from each equation.
| Reps to failure | Epley | Brzycki | Lombardi |
|---|---|---|---|
| 1 | 100% | 100% | 100% |
| 2 | 93.8% | 97.2% | 93.3% |
| 3 | 90.9% | 94.4% | 89.6% |
| 4 | 88.2% | 91.7% | 87.1% |
| 5 | 85.7% | 88.9% | 85.1% |
| 6 | 83.3% | 86.1% | 83.6% |
| 7 | 81.1% | 83.3% | 82.3% |
| 8 | 78.9% | 80.6% | 81.2% |
| 9 | 76.9% | 77.8% | 80.3% |
| 10 | 75.0% | 75.0% | 79.4% |
| 12 | 71.4% | 69.4% | 78.0% |
| 15 | 66.7% | 61.1% | 76.3% |
Epley and Brzycki agree exactly at 10 reps (75%) and stay within about 3.5 points of each other from 2 to 12 reps. Lombardi flattens out, so above 10 reps it predicts a lower 1RM than the others. This is why estimates from sets of 3 to 6 reps are the most dependable.
Worked Example: 225 lb for 5 Reps
- Epley: 225 × (1 + 5 ÷ 30) = 262.5 lb
- Brzycki: 225 × 36 ÷ (37 − 5) = 253.1 lb
- Lander: 100 × 225 ÷ (101.3 − 2.67123 × 5) = 255.8 lb
- Lombardi: 225 × 50.10 = 264.3 lb
- Mayhew: 100 × 225 ÷ (52.2 + 41.9 × e−0.275) = 267.8 lb
- O'Conner: 225 × (1 + 0.025 × 5) = 253.1 lb
- Wathan: 100 × 225 ÷ (48.8 + 53.8 × e−0.375) = 262.3 lb
The average of the seven is 259.9 lb, and the spread is about 15 lb. The calculator rounds to the nearest 2.5 lb, so it shows 262.5 lb for Epley and 260 lb for the average.
Training loads from a 262.5 lb 1RM
| % of 1RM | Weight (nearest 2.5 lb) | Typical use |
|---|---|---|
| 90% | 237.5 lb | Heavy singles, doubles and triples |
| 85% | 222.5 lb | Strength sets of about 5 |
| 80% | 210 lb | Sets of 6 to 8 |
| 75% | 197.5 lb | Sets of 8 to 10 |
| 70% | 185 lb | Sets of 10 to 12 |
| 60% | 157.5 lb | Technique and warm-up work |
Common 1RM Mistakes
- Using a set that was not hard. The formulas assume you could not have done another rep. If you stopped with 2 reps left, add them to the rep count or the estimate will be too low.
- Estimating from high reps. From a set of 15 the formulas disagree by more than 20%, as the table above shows. Use a heavier set of 3 to 6.
- Programming from the full estimate. Many programs, 5/3/1 among them, take percentages of a training max of about 90% of your 1RM, not of the 1RM itself.
- Mixing lifts. An estimate is only valid for the lift you tested. Your squat 1RM tells you nothing about your overhead press.
These are estimates. If you test a true single, warm up well and use a spotter or safety bars. If you have a heart condition, high blood pressure or an injury, ask your doctor before maximal lifting.
Method and sources. Formulas: Epley B (1985), Brzycki M (1993), Lander J (1985), Lombardi VP (1989), Mayhew JL et al. (1992), O'Conner B et al. (1989) and Wathan D (1994), as implemented in the calculator. Every percentage and weight above was computed with the same equations and the same 2.5 lb rounding the calculator uses. Estimates only, not medical or coaching advice.
1RM formulas are estimates. Actual 1RM may differ due to technique, fatigue, individual fiber type ratio, and training status. Never attempt a true 1RM test without a spotter and adequate warm-up. This calculator is for training programming, not competition preparation.
One Rep Max Questions
A one rep max (1RM) is the maximum weight you can lift for exactly one complete repetition with proper form. It is the gold standard measure of absolute strength for a given exercise. 1RM is used to set training loads as percentages (e.g., "work up to 80% of 1RM for 3 sets of 5") in strength and powerlifting programs. Directly testing 1RM requires adequate warm-up, a spotter for upper body lifts, and experience with the movement. For most people, estimating 1RM from a submaximal test (3-6 reps) is safer and sufficient for programming purposes.
No single formula is universally the most accurate: each was validated on different populations. The Epley formula (1 + reps/30) is the most commonly used in practice and tends to perform well for sets of 1-10 reps. Brzycki is considered slightly more accurate in the 2-6 rep range. Mayhew et al. and Wathan were validated specifically on college athletes. The best approach is to use the average of multiple formulas, which averages out individual formula biases. For any individual, comparing your estimated 1RM to actual tested 1RM and noting which formula comes closest helps you calibrate your estimates over time.
The most accurate 1RM estimates come from sets of 2-6 reps. This is because these sets are primarily limited by maximal force production (neural drive, muscle fiber recruitment) rather than muscular endurance or cardiovascular capacity. Above 8-10 reps, endurance becomes increasingly influential, and people vary much more in their endurance relative to their maximum strength. A person who can bench 225 lbs once may be able to do 5 reps (expected) or 12 reps (very high endurance) depending on their fiber type. Below 10 reps, this variation is much smaller.
Training zones by percentage of 1RM: 90-100% (1-3 reps), maximal strength, competition peaking, neural adaptation. 80-90% (2-5 reps): strength development, powerlifting programming. 70-80% (5-8 reps): strength and hypertrophy overlap, most commonly used range. 60-70% (8-15 reps): hypertrophy (muscle size), metabolic stress. 50-60% (15-30 reps): muscular endurance, conditioning. Below 50%: technique work, warm-up, rehabilitation. Most general strength programs operate primarily in the 70-85% range.
Safe 1RM testing protocol: (1) Perform a thorough warm-up with your specific lift, multiple sets ramping up in weight, finishing with 1-2 reps at about 90% of your expected 1RM. (2) Rest 3-5 minutes between heavy warm-up sets. (3) Attempt the weight you believe is your 1RM. (4) If successful, rest 3-5 minutes and increase by 5-10 lbs for upper body or 10-20 lbs for lower body. (5) Never test 1RM alone: always use a spotter or safety bars/arms in the rack. (6) Only attempt 1RM when fully rested (at least 48 hours from last training). (7) Use a weight you are confident in your technique with.
For beginners, 1RM can increase weekly (linear progression is possible). For intermediate lifters (6-18 months of training), monthly progress is typical. For advanced lifters, significant 1RM gains may occur over 3-6 month training cycles. 1RM also fluctuates day-to-day based on sleep, nutrition, stress, and cumulative fatigue. A well-rested, fully recovered lifter may test 5-10% higher than the same person in a fatigued state. This is why peaking protocols (reducing volume while maintaining intensity before a competition) aim to express maximal strength on a specific day.
No. Beginners should not attempt true 1RM tests. The reasons: (1) Injury risk is significantly higher due to unfamiliarity with the movement pattern under maximal load. (2) Beginners are in a linear progression phase where 1RM testing is unnecessary: they improve every session and can track progress through training weights. (3) The formula-based estimates from a 5RM or 3RM are entirely sufficient for programming. (4) True 1RM testing is most relevant for competitive powerlifters and weightlifters who need to know their competition maxes. For general fitness goals, use the calculator to estimate 1RM from submaximal sets and program at appropriate percentages.
General strength standards by bodyweight (for trained men): Squat, intermediate: 1.5x bodyweight, advanced: 2x. Bench press, intermediate: 1x bodyweight, advanced: 1.5x. Deadlift, intermediate: 2x bodyweight, advanced: 2.5x. Overhead press, intermediate: 0.75x bodyweight, advanced: 1x. For trained women, these numbers are approximately 20-30% lower proportionally. These are rough guidelines: individual proportions, limb lengths, and training history significantly affect these ratios.
Once you have your estimated 1RM, calculate working weights using percentages. Example for a 5/3/1-style program with a 225 lb bench 1RM, using a training max of 90% (202.5 lbs) and rounding to 5 lbs: Week 1 (65/75/85%): 130/150/170 lbs. Week 2 (70/80/90%): 140/160/180 lbs. Week 3 (75/85/95%): 150/170/190 lbs. For hypertrophy, use 65-75% for 3-4 sets of 8-12 reps. For strength, use 80-90% for 3-5 sets of 2-5 reps. Program design note: most programs use 90% of your true 1RM as the "training max" to account for daily variation and ensure you can complete programmed sets on bad days.
This is common and has several explanations. (1) High-rep estimation is unreliable: if the rep test was 12+ reps, endurance masking means the formula overestimates true max strength. (2) Technique breakdown under maximal load: you may rep out 315 lbs for 5 reps but fail 370 lbs (the estimated 1RM) because maximal single attempts require a different neural pattern and technique cue than submaximal sets. (3) Individual fiber type ratio: people with more slow-twitch fibers can sustain higher rep percentages of their 1RM, causing all formulas to overestimate. (4) Psychological factors: many lifters can physically lift more than they can psychologically commit to on a single max attempt.
Multiply the weight by about 1.13 to 1.17. Brzycki uses 1.125 for 5 reps and Epley uses 1.167. So 185 lb for 5 reps gives an estimated max of about 208 lb (Brzycki) to 216 lb (Epley). The set needs to be close to failure for the estimate to hold.
About 75%. Epley and Brzycki both put a 10 rep max at exactly 75% of your one rep max, so 150 lb for 10 reps points to a 1RM of about 200 lb. Individual endurance varies, so people with more endurance can often do 10 reps at a higher share of their max.