One Rep Max (1RM) Calculator
Estimate your maximum strength for any lift without risking injury. Enter your working weight and reps to get your 1RM and full training percentage table.
Calculate Your 1RM
Most accurate with 1–10 reps. Results become less reliable above 10 reps.
Estimated 1RM
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lbs (average of 3 formulas)
Epley
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Brzycki
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Lander
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Training Percentage Table
| % of 1RM | Weight (lbs) |
|---|
What Is 1RM and Why It Matters
Your one rep max (1RM) is the maximum amount of weight you can lift for a single repetition with proper form on a given exercise. It's the gold standard measurement of absolute strength in powerlifting and strength training, and it forms the foundation for almost all evidence-based programming.
Knowing your 1RM allows you to train at precise intensities — rather than guessing whether a weight "feels heavy," you can program your workouts based on exact percentages of your maximum capacity. This is how elite strength coaches and athletes plan their training blocks.
Most people shouldn't regularly test their true 1RM due to injury risk, especially for beginners. Instead, this calculator lets you estimate your 1RM from a set of multiple reps performed to near-failure — a much safer and still highly accurate approach.
How the Three Formulas Differ
- Epley (1985): weight × (1 + reps/30). One of the most widely used formulas. Tends to slightly overestimate at high reps.
- Brzycki (1993): weight × 36/(37 - reps). Considered very accurate for lower rep ranges (1-10 reps). Breaks down above 10 reps.
- Lander: weight × 100/(101.3 - 2.67123 × reps). Provides a middle-ground estimate, particularly reliable for 3-8 rep ranges.
Using % of 1RM for Programming
Powerlifting (Strength Focus)
Strength training programs typically operate in the 70-95% of 1RM range for primary movements:
- 85-95%: 1-3 reps — maximal strength, neural adaptations
- 75-85%: 3-6 reps — strength-hypertrophy overlap
- 70-75%: 5-8 reps — primary strength building zone
Programs like 5/3/1, Sheiko, and conjugate periodization all rely heavily on percentage-based loading derived from your 1RM.
Bodybuilding (Hypertrophy Focus)
Bodybuilding training typically uses lighter relative loads with higher volume:
- 60-75%: 8-12 reps — primary hypertrophy range
- 50-65%: 12-20 reps — metabolic stress, pump
- 70-80%: 6-8 reps — strength-size overlap
Research shows hypertrophy occurs across a wide rep range (5-30 reps) as long as sets are taken close to failure. The 8-12 range is simply efficient for volume accumulation.
When to Test Your True 1RM Safely
If you want to test an actual 1RM: warm up thoroughly with progressively heavier sets (50%, 70%, 80%, 90%), rest 3-5 minutes between attempts, have a spotter for bench press, and only attempt a true max after several months of consistent training. Beginners should wait at least 6-12 months before attempting 1RM testing on compound lifts.
Related Calculators
Frequently Asked Questions
1RM calculators are most accurate when based on sets of 1-5 reps. Accuracy decreases significantly as rep count increases — by 10-15 reps, the estimate can be off by 10-15% or more. This is because the relationship between reps and maximal strength varies by individual — some people are "rep-strong" (can do many reps at a high % of 1RM) while others fatigue more quickly. Using the average of multiple formulas, as this calculator does, generally improves accuracy compared to any single formula.
Percentage-based programming is most valuable for compound movements: squat, bench press, deadlift, overhead press, and barbell row. For isolation exercises (curls, lateral raises, cable work), RPE (Rate of Perceived Exertion) or rep-range based loading is typically more practical. Most serious programs use 1RM percentages for main compound movements and RPE or rep ranges for accessory work. Calculate your 1RM for the lifts you track and compete on, not every exercise in your program.
For beginners, 1RM can increase meaningfully every 2-4 weeks. For intermediate lifters, monthly progress is realistic. Advanced lifters might see 1RM improvements every few months. Recalculate whenever your working weights change significantly — if your 5-rep weight goes up by 10 lbs, your estimated 1RM also increases. Many lifters recalculate at the start of each training block (every 4-8 weeks) to keep programming percentages accurate and progressive.
Strength standards vary by bodyweight, sex, and training age. As rough benchmarks for adult men: Beginner — bench 1× bodyweight, squat 1.25×, deadlift 1.5×. Intermediate — bench 1.25×, squat 1.5×, deadlift 2×. Advanced — bench 1.5×, squat 2×, deadlift 2.5×. For women, multiply these benchmarks by approximately 0.6-0.7 due to differences in upper body to lower body strength ratios and hormonal differences affecting absolute strength. These are general guidelines — great athletes exist at every level.
RPE (Rate of Perceived Exertion) on a 1-10 scale is an alternative to percentage-based loading. RPE 10 means you couldn't do another rep (essentially your max), RPE 9 means 1 rep in reserve, RPE 8 means 2 reps in reserve, etc. Many modern powerlifting programs use RPE because it auto-regulates for daily performance variation — on a bad day (poor sleep, high stress), your RPE 8 might be at a lower absolute weight, which is appropriate. Percentage-based and RPE approaches can complement each other: use percentages to set initial weights, then adjust based on how it feels (RPE) that day.