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Reviewed by CalculatorApp.me Health Team
Epley, Brzycki, and Lombardi formulas, rep-percentage charts, progressive overload, periodization models, and strength standards.
1RM
Maximum single lift
~85%
5-rep max percentage
2-3 min
Rest for strength sets
1-2%/wk
Progressive overload rate
Free one rep max (1RM) calculator — estimate your max lift using Epley, Brzycki, Lander, or Lombardi formulas with AI-powered training insights.
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The one-repetition maximum (1RM) is the maximum weight a person can lift for a single repetition with proper form. It is the gold standard for measuring absolute muscular strength and is used to prescribe training loads as percentages (e.g., "work at 75% of your 1RM"). Knowing your 1RM allows precise programming for hypertrophy, strength, power, or endurance goals.
Rather than testing a true 1RM (which carries injury risk and requires maximal effort), most athletes estimate it from a submaximal set — lifting a lighter weight for multiple reps and applying a prediction formula. Research shows that sets of 3-10 reps provide the most accurate predictions; sets above 12 reps progressively underestimate true 1RM because endurance factors begin to dominate.
The 1RM is exercise-specific and muscle-group-specific — your squat 1RM says nothing about your bench press 1RM. Ratios between lifts (e.g., squat should be ~1.2-1.5× bench) can reveal imbalances and guide programming priorities.
1RM = w × (1 + r/30) Where: w = weight lifted r = number of repetitions Example: 225 lbs × 5 reps 1RM = 225 × (1 + 5/30) 1RM = 225 × 1.1667 1RM = 262.5 lbs Percentage calculation: %1RM = 1 / (1 + r/30) × 100 Rep → %1RM mapping: 1 rep = 100% (actual max) 3 reps = 90.9% 5 reps = 85.7% 8 reps = 78.9% 10 reps = 75.0% 12 reps = 71.4% 15 reps = 66.7% 20 reps = 60.0%
Published by Boyd Epley (1985). The most widely used formula due to simplicity. Slightly overestimates for very low reps and underestimates for very high reps.
1RM = w × (36 / (37 − r)) Equivalently: 1RM = w / (1.0278 − 0.0278 × r) Example: 225 lbs × 5 reps 1RM = 225 × (36/(37−5)) 1RM = 225 × (36/32) 1RM = 225 × 1.125 1RM = 253.1 lbs %1RM from reps: %1RM = (37 − r) / 36 × 100 Rep → %1RM: 1 rep = 100% 3 reps = 94.4% 5 reps = 88.9% 8 reps = 80.6% 10 reps = 75.0% 12 reps = 69.4% 15 reps = 61.1% Note: Becomes undefined at 37 reps (mathematical limit of the formula)
Published by Matt Brzycki (1993). Tends to produce more conservative estimates than Epley. Particularly accurate for sets of 1-10 reps.
Lombardi (1989):
1RM = w × r^0.10
O'Conner et al. (1989):
1RM = w × (1 + 0.025 × r)
Mayhew et al. (1992):
1RM = w / (0.522 + 0.419 × e^(−0.055 × r))
Example: 225 lbs × 5 reps:
Lombardi:
= 225 × 5^0.10
= 225 × 1.175
= 264.3 lbs
O'Conner:
= 225 × (1 + 0.025 × 5)
= 225 × 1.125
= 253.1 lbs
Mayhew:
= 225 / (0.522 + 0.419 × e^−0.275)
= 225 / 0.840
= 267.8 lbs| Reps | % 1RM (Epley) | % 1RM (Brzycki) | Training Goal | Sets | Rest Period |
|---|---|---|---|---|---|
| 1 | 100% | 100% | Maximal Strength | 1-3 | 3-5 min |
| 2 | 93.5% | 94.4% | Strength / Power | 3-5 | 3-5 min |
| 3 | 90.9% | 91.7% | Strength | 3-5 | 3-5 min |
| 4 | 88.2% | 88.9% | Strength | 3-5 | 2-4 min |
| 5 |
| Lift | Beginner | Novice | Intermediate | Advanced | Elite |
|---|---|---|---|---|---|
| Back Squat (M) | 0.75×BW | 1.25×BW | 1.75×BW | 2.5×BW | 3.0×BW |
| Back Squat (F) | 0.50×BW | 0.75×BW | 1.25×BW | 1.75×BW | 2.25×BW |
| Bench Press (M) | 0.50×BW | 1.0×BW | 1.5×BW | 2.0×BW | 2.5×BW |
| Bench Press (F) | 0.35×BW | 0.65×BW | 1.0×BW | 1.5×BW | 1.75×BW |
The legendary Greek wrestler Milo reportedly carried a growing calf daily until it became a bull — the earliest description of progressive overload. While likely embellished, the principle (gradually increasing load) remains the most fundamental concept in strength training.
US Army physician Thomas DeLorme published his progressive resistance exercise protocol for rehabilitating injured soldiers. He established the concept of training with percentages of maximum capacity and prescribed 3 sets of 10 repetitions — a structure (3×10) that remains the most common gym prescription today.
Boyd Epley, strength coach at the University of Nebraska, published his 1RM prediction formula: 1RM = w × (1 + r/30). Its simplicity made it the most widely adopted formula. It allowed coaches to prescribe training loads from submaximal tests, reducing injury risk from maximal testing.
Matt Brzycki proposed the formula 1RM = w × 36/(37−r), which produces more conservative estimates at higher rep ranges. Research comparing formulas found Brzycki slightly more accurate for bench press, while Epley better predicted squat and deadlift 1RM.
Schoenfeld et al. — JSCR (2017)
Meta-analysis of 21 studies: loads ≥60% 1RM produced equivalent hypertrophy to loads ≥85% 1RM when volume was equated. However, heavier loads (85%+) were significantly superior for 1RM strength gains. This supports using the 1-5 rep range for strength and 6-12+ for hypertrophy.
LeSuer et al. — JSCR (1997)
Compared Epley, Brzycki, Mayhew, O'Conner, and Lombardi formulas against actual 1RM in bench press, squat, and deadlift. All formulas were most accurate with 3-5 reps (±5-7%). Accuracy decreased above 10 reps. No single formula was universally superior — averaging multiple formulas improved accuracy.
Grgic et al. — Sports Med (2020)
Systematic review: rest periods of 3-5 minutes between sets produced greater strength gains than 1-2 minutes. For hypertrophy, shorter rest (60-90 seconds) was equally effective due to greater metabolic stress. For 1RM testing, 3-5 minutes between attempts is recommended.
Peterson et al. — MSSE (2005)
You must train heavy (1-3 reps) to build muscle.
Hypertrophy occurs across a wide rep range (6-30+ reps) as long as sets are taken close to failure. Research shows similar muscle growth at 30% vs 85% 1RM when volume is equated. However, heavy training (85%+) IS superior for maximal strength (1RM) gains.
Testing your 1RM is dangerous and unnecessary.
While maximal testing carries higher injury risk than submaximal training, proper preparation (warm-up, progressive loading, spotters) makes it safe. However, 1RM estimation formulas make direct testing unnecessary for most trainees. True 1RM testing is mainly needed for competitive powerlifters.
You should always train to failure for maximum gains.
Training to failure is not required for strength or hypertrophy gains — leaving 1-3 reps in reserve (RPE 7-9) produces similar results with better recovery. Consistently training to failure increases CNS fatigue, extends recovery time, and may increase injury risk. Reserve failure for isolation exercises and deload periods.
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Multiple formulas exist because 1RM prediction depends on training status, muscle fiber type, and exercise type. Averaging 2-3 formulas improves accuracy.
Comparison at 225 lbs × 5 reps: Epley: 262.5 lbs Brzycki: 253.1 lbs Lombardi: 264.3 lbs O'Conner: 253.1 lbs Mayhew: 267.8 lbs Average: 260.2 lbs Accuracy factors: • Rep range: 1-5 reps most accurate • Training level: Trained > untrained • Exercise: Compound > isolation • Muscle groups: Legs > chest > arms Best practices: 1. Test with 3-5 reps for accuracy 2. Use the same formula consistently 3. Average 2-3 formulas for planning 4. Actual 1RM testing trumps formulas 5. Retest every 4-8 weeks of training Real-world accuracy: ±5% for 3-5 reps (well-trained) ±10% for 8-12 reps ±15%+ for 15+ reps
Research by LeSuer et al. (1997) found that no single formula is superior for all exercises. Brzycki and Epley are most widely validated.
| 85.7% |
| 86.1% |
| Strength |
| 3-5 |
| 2-4 min |
| 6 | 83.3% | 83.3% | Strength-Hypertrophy | 3-4 | 2-3 min |
| 8 | 78.9% | 77.8% | Hypertrophy | 3-5 | 1.5-2 min |
| 10 | 75.0% | 72.2% | Hypertrophy | 3-4 | 1-2 min |
| 12 | 71.4% | 66.7% | Hypertrophy-Endurance | 2-3 | 60-90 sec |
| 15 | 66.7% | 61.1% | Muscular Endurance | 2-3 | 30-60 sec |
| 20 | 60.0% | 52.8% | Endurance | 2-3 | 30-60 sec |
| Deadlift (M) |
| 1.0×BW |
| 1.5×BW |
| 2.0×BW |
| 2.75×BW |
| 3.5×BW |
| Deadlift (F) | 0.65×BW | 1.0×BW | 1.5×BW | 2.25×BW | 2.75×BW |
| OHP (M) | 0.35×BW | 0.65×BW | 1.0×BW | 1.35×BW | 1.65×BW |
| OHP (F) | 0.25×BW | 0.45×BW | 0.65×BW | 0.90×BW | 1.15×BW |
BW = body weight. Standards based on Symmetric Strength and ExRx.net data for healthy adults. M = Male, F = Female, OHP = Overhead Press.
Soviet weightlifting coach Alexander Prilepin's research on optimal training volumes (number of reps at each intensity) was widely disseminated. His chart prescribes 1-3 reps at 90%+ 1RM (4-10 total reps), 3-6 reps at 80-89% (10-20 total), and 3-6 reps at 70-79% (12-24 total).
Schoenfeld et al. published a meta-analysis showing that both heavy (85%+ 1RM) and moderate (60-80% 1RM) loads produce similar hypertrophy when volume is equated — but heavy loads are superior for maximal strength gains. This validated the use of moderate loads for muscle growth.
Meta-analysis of 177 studies: trained athletes need higher intensities (85%+ 1RM) for maximal strength gains than untrained individuals (60% 1RM sufficient). Frequency of 2×/week per muscle group was superior to 1× or 3×. Periodization models significantly outperformed constant loading.
Women get 'bulky' from heavy lifting.
Women produce ~15-20× less testosterone than men, making excessive muscle gain virtually impossible. Heavy lifting increases strength, bone density, and muscle tone without dramatic size increases. Most female strength athletes train heavy and maintain lean, athletic physiques.