One Rep Max Calculator
Enter the weight you lifted and how many reps you completed. The calculator estimates your one-rep maximum (1RM) using five established formulas and shows your training zones.
| Formula | Estimated 1RM |
|---|---|
| Epley | 116.7 lbs |
| Brzycki | 112.5 lbs |
| Lander | 113.7 lbs |
| Lombardi | 117.5 lbs |
| Mayhew et al. | 119.0 lbs |
| Average | 115.9 lbs |
Weight lifted (w) = 100.0 lbs, Reps (r) = 5 Epley: w × (1 + r/30) = 100.0 × (1 + 5/30) = 100.0 × 1.1667 = 116.7 lbs Brzycki: w × 36/(37−r) = 100.0 × 36/32 = 100.0 × 1.1250 = 112.5 lbs Lander: w × 100/(101.3−2.67123×r) = 100.0 × 100/87.944 = 113.7 lbs Lombardi: w × r^0.10 = 100.0 × 5^0.10 = 100.0 × 1.1746 = 117.5 lbs Mayhew: w × 100/(52.2 + 41.9×e^(−0.055×r)) = 119.0 lbs Average of 5 formulas = 115.9 lbs
| Goal | % of 1RM | Weight (lbs) | Reps |
|---|---|---|---|
| Strength | 90% | 104.3 | 1–3 |
| Power | 80% | 92.7 | 3–5 |
| Hypertrophy | 70% | 81.1 | 8–12 |
| Endurance | 60% | 69.5 | 15–20 |
| Warm-up | 50% | 57.9 | 10–15 |
For informational purposes only. Consult a healthcare professional before beginning any strength training program.
| Level | Men (kg) | Women (kg) |
|---|---|---|
| Beginner | 70 | 40 |
| Novice | 90 | 52 |
| Intermediate | 100 | 60 |
| Advanced | 140 | 90 |
| Elite | 180 | 115 |
What is a One-Rep Max (1RM)?
A one-rep max, abbreviated 1RM, is the maximum load you can lift for exactly one complete repetition of a given exercise while maintaining proper technique. It represents your absolute ceiling of strength on that movement at that moment in time.
The 1RM is the primary unit of measurement in powerlifting competitions, where athletes attempt squat, bench press, and deadlift for a single maximum effort lift. In broader strength training, the 1RM serves as the reference point from which all training loads are derived. Instead of prescribing "lift 80 kg," coaches prescribe "lift 75% of your 1RM" — a percentage that scales automatically as the athlete grows stronger.
Because directly testing a 1RM carries injury risk — maximum loads stress tendons, ligaments, and joints at their limit — coaches frequently use sub-maximal sets to estimate the 1RM mathematically. This approach is safer, easier to perform regularly, and still provides useful training data.
The Five 1RM Estimation Formulas
Multiple formulas exist because no single equation is optimal for every person, every exercise, or every rep range. Using several formulas and averaging the results improves accuracy.
Epley Formula (1985)
1RM = weight × (1 + reps ÷ 30)
Developed by Boyd Epley, strength coach at the University of Nebraska. One of the oldest and most widely cited formulas. It tends to slightly overestimate at very high rep counts but is reliable in the 1–10 rep range.
Brzycki Formula (1993)
1RM = weight × 36 ÷ (37 − reps)
Matt Brzycki's formula is popular in strength and conditioning programs. It produces similar results to Epley at low rep counts but diverges at higher reps. Note that the formula becomes undefined at 37 reps, so it is only valid for 1–36 reps.
Lander Formula (1985)
1RM = weight × 100 ÷ (101.3 − 2.67123 × reps)
Developed by John Lander. Produces estimates between the Epley and Brzycki values at moderate rep ranges.
Lombardi Formula (1989)
1RM = weight × reps0.10
A power-based formula by Lombardi. It tends to give slightly lower estimates than the other formulas at moderate rep counts. Some find it more conservative and therefore safer when setting training loads.
Mayhew et al. Formula (1992)
1RM = weight × 100 ÷ (52.2 + 41.9 × e−0.055 × reps)
Published by Mayhew, Ball, Arnold, and Bowen. Uses an exponential decay function. Originally developed for the bench press specifically, but is applied broadly.
How Accurate Are These Formulas?
Research consistently shows that all 1RM prediction formulas are more accurate when based on lower rep sets. The relationship between reps and 1RM percentage is not perfectly linear — it varies by:
- Exercise type — multi-joint compound lifts (squat, deadlift) behave differently from isolation exercises (bicep curl)
- Individual training history — highly trained individuals can perform more reps at a given percentage than beginners
- Muscle fiber composition — those with more slow-twitch fibers perform better at higher rep sets relative to their 1RM
- Rep range used — formulas are most accurate at 2–6 reps and lose accuracy above 10 reps
For programming purposes, treat estimated 1RM as a useful approximation, not an exact value. Always adjust weights based on how the actual training sets feel.
Percentage-Based Training Zones
Once you know your estimated 1RM, you can structure your entire training program around percentages. This is called percentage-based programming (or percent-based training, PBT). Different rep and load combinations produce different physiological adaptations:
| Zone | % of 1RM | Reps | Primary Adaptation |
|---|---|---|---|
| Absolute strength | 93–100% | 1–2 | Maximal neural activation, CNS adaptation |
| Strength | 85–93% | 2–4 | Strength gains, some muscle mass |
| Power | 75–85% | 3–6 | Strength-speed, force-velocity improvements |
| Hypertrophy | 67–75% | 8–12 | Maximum muscle growth (metabolic stress + mechanical tension) |
| Muscular endurance | 50–67% | 15–25 | Capillary density, mitochondrial adaptations |
Most well-designed programs rotate between these zones across a training cycle. A common 16-week block might spend 4 weeks in the hypertrophy zone (building volume tolerance), 4 weeks in the power zone, 4 weeks in the strength zone, and 4 weeks peaking toward a 1RM test or competition. This approach, called periodization, prevents accommodation and ensures continued progress.
Powerlifting Strength Standards
Strength standards give context to your numbers. They differ by sex, body weight, and competition federation. The table in the calculator shows squat standards as a rough reference. For bench press, divide roughly by 1.5. For deadlift, add roughly 30–40% compared to squat standards.
Popular powerlifting federations include the IPF (International Powerlifting Federation), USPA (United States Powerlifting Association), and RPS. Each uses different weight classes and drug-testing policies, which affects what constitutes "elite" in their system.
Safety Guidelines for 1RM Testing
If you choose to test your actual 1RM rather than estimate it, follow these safety guidelines:
- Complete a comprehensive warm-up: 5–10 minutes of cardio (use our Heart Rate Zone Calculator to target Zone 1–2) followed by progressively heavier sets
- Start at 50–60% of estimated 1RM for your first warm-up set, then make jumps of 10–15%
- Rest 3–5 minutes between your last warm-up set and your first true attempt
- Rest 3–5 minutes between attempts — do not rush
- Make 2–3 attempts maximum to avoid fatigue-related injury
- Always use collars to prevent plates sliding off the bar
- Use safety bars or a competent spotter for squat and bench press
- Do not attempt a 1RM when fatigued, sleep-deprived, or after a high-volume training session
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 complete repetition of a given exercise with proper form. It is the gold standard for measuring absolute strength in powerlifting and strength training. Knowing your 1RM allows you to set training loads as precise percentages, rather than guessing.
Which 1RM formula is the most accurate?
No single formula is most accurate for all people. The Epley and Brzycki formulas are the most widely used. Research shows that accuracy decreases as repetitions increase beyond 5–6 reps, because factors like muscular endurance and anaerobic capacity become more important. For the highest accuracy, use a low rep set (3–5 reps) and average the results from multiple formulas.
How do I test my 1RM safely?
To test your actual 1RM: (1) Warm up thoroughly with progressively heavier sets. (2) Make jumps of 5–10% between attempts. (3) Rest 3–5 minutes between heavy attempts. (4) Always use a spotter for bench press and squat. (5) Use a power rack with safety bars. Most coaches recommend estimated 1RM testing via sub-maximal sets rather than true max attempts, especially for beginners, to reduce injury risk.
What percentage of 1RM should I train at?
Training zones based on 1RM percentage: 90–100% for maximal strength (1–3 reps), 80–90% for strength and power (3–5 reps), 67–80% for hypertrophy and muscle growth (6–12 reps), 50–67% for muscular endurance (15–20 reps). Most programs rotate through these zones over a training cycle (periodization).
How often should I test my 1RM?
Testing your 1RM directly is taxing on the central nervous system and joints, so most athletes test their actual max every 8–16 weeks (at the end of a training block). Between formal tests, you can track progress using estimated 1RM calculations from your working sets — if you add weight or reps to your 5RM set, your estimated 1RM improves.
Medical Disclaimer: For informational purposes only. Consult a healthcare professional before beginning any strength training program, particularly if you have existing injuries, joint problems, or cardiovascular conditions. Maximal lifting carries inherent injury risk. Always train with proper supervision and technique.
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