One Rep Max Calculator

Your one rep max (1RM) is the maximum amount of weight you can lift for a single repetition with proper form. It represents your peak strength for a given exercise. Knowing your 1RM is essential for programming training percentages, tracking progress, and setting goals. Rather than testing your actual max (which can be dangerous), most lifters estimate it using submaximal weights and rep-based formulas.

1RM formulas are most accurate with lower rep ranges (1-6 reps), with accuracy decreasing as reps increase. Research shows formulas tend to overestimate 1RM when based on 10+ reps. The Epley and Brzycki formulas are most commonly used and validated. Accuracy also varies by individual—trained lifters' estimates tend to be more accurate than beginners'. For best results, use a weight you can lift for 3-5 reps with good form.

EPLEY: w × (1 + r/30) — Most popular, simple, good for moderate reps. BRZYCKI: w × (36/(37-r)) — Very accurate for low reps (1-10). LANDER: 100w / (101.3 - 2.67r) — Widely used in research. LOMBARDI: w × r^0.10 — Simpler exponential model. MAYHEW: Regression-based, validated for football players. O'CONNER: More conservative estimate. WATHAN: Accurate across rep ranges. Most formulas give similar results for 1-5 reps but diverge at higher rep counts.

For most people, the Epley or Brzycki formula works well. Brzycki tends to be more accurate for low rep ranges (1-6), while Epley works better across all rep ranges. If you want the most reliable estimate, compare multiple formulas and use the average. Our calculator shows all 7 formulas so you can see the range of estimates.

Strength standards compare your lift to your bodyweight to classify your level. For example, benching 1.5x your bodyweight is typically considered 'Advanced.' Standards vary by exercise: Squat and deadlift standards are higher than bench press. The 5 levels are: BEGINNER (just starting), NOVICE (few months training), INTERMEDIATE (1-2 years consistent), ADVANCED (many years dedicated), ELITE (competitive level). Standards also differ by sex—female standards use different multipliers.

Training percentages express working weight as a percentage of your 1RM. They determine training intensity and rep ranges: 85-100% (1-5 reps) = Maximal strength development. 70-85% (5-8 reps) = Strength and some hypertrophy. 65-80% (8-12 reps) = Hypertrophy (muscle growth). 50-65% (12-20 reps) = Muscular endurance. Most strength programs prescribe percentages for each workout (e.g., '5x5 at 75%').

A proper warm-up prepares muscles and nervous system for heavy loads. Start with: (1) 5-10 min general cardio to raise body temperature. (2) Dynamic stretching for target muscles. (3) Empty bar set for 10 reps. (4) Progressive loading: 50% x 8, 60% x 5, 70% x 3, 85% x 1-2. (5) Rest 2-3 minutes before working sets. Our warm-up calculator provides specific weights based on your planned working weight.

Testing actual 1RM is taxing on the body and carries injury risk. Most lifters test every 8-16 weeks at the end of a training block. For programming purposes, you can estimate your 1RM more frequently using submaximal sets (e.g., if you hit a new 5-rep PR, recalculate your estimated 1RM). Avoid true max testing when fatigued, during deload weeks, or if returning from injury.

Formulas become less accurate as reps increase because the relationship between submaximal weight and max strength isn't perfectly linear. Other factors come into play: muscle endurance, technique under fatigue, cardiovascular conditioning, and mental fatigue. That's why testing with 3-5 reps gives more reliable estimates than 10+ reps. If you notice big discrepancies, use the lower rep count as your basis.

Your estimated 1RM may be too high if you can't hit prescribed percentages. This could happen because: (1) The formula overestimated based on high-rep input. (2) You're fatigued or recovering poorly. (3) You've lost strength (happens during cuts or time off). (4) Technical breakdown at higher weights. Adjust by re-testing with lower reps, or simply reduce your working 1RM by 5-10% until percentages feel appropriate.

No, strength standards differ between sexes due to physiological differences (muscle mass, hormone levels, body composition). Female standards use lower bodyweight multipliers while maintaining the same classification tiers (Beginner through Elite). For example, a 1x bodyweight bench might be 'Intermediate' for women but below that for men. Our calculator currently uses male standards—female-specific standards vary and should be researched separately.

Progressive overload is key: (1) Add small weight increments weekly (2.5-5 lbs for upper, 5-10 lbs for lower). (2) Follow a periodized program alternating volume and intensity phases. (3) Prioritize recovery—sleep, nutrition, stress management. (4) Track all workouts to identify stalls. (5) Deload every 4-6 weeks. (6) Address weak points with accessory work. Beginners may add 5-10 lbs/week; intermediates 5-10 lbs/month; advanced lifters fight for 5-10 lbs/year.

STRENGTH (1-5 reps, 85-100% 1RM): Maximizes neural adaptations and peak force production. Best for powerlifters. HYPERTROPHY (6-12 reps, 65-80% 1RM): Optimal for muscle growth. Creates metabolic stress and mechanical tension. What most bodybuilders use. ENDURANCE (12-20+ reps, 50-65% 1RM): Builds muscular endurance, less strength/size. Good for rehab or conditioning. Most programs combine ranges for balanced development.

Yes, always round to the nearest weight you can actually load. Most gyms have plates in 2.5 lb / 1.25 kg increments, so round to the nearest 5 lbs or 2.5 kg. For micro-loading (small increments), you can buy fractional plates (0.25-1.25 lbs). When in doubt, round DOWN to ensure you can complete the prescribed reps with good form.

No. This calculator runs entirely in your browser. Your lift data is processed locally on your device and is never sent to our servers or stored anywhere. When you close or refresh the page, all data is cleared. Your training information stays private.