Strength Training

One Rep Max
Calculator

Estimate your 1RM using 7 formulas. Get training percentages, rep range estimator, and formula comparison for Bench, Squat, Deadlift, and OHP.

—

Est. 1RM

—

80% (4–6 rep)

—

70% (8–10 rep)

Lift Details

Weight Lifted 100 kg

Reps Performed 5 reps

reps

Each side: —

Estimated 1 Rep Max

—

Average of 7 formulas

90% 1RM

—

80% 1RM

—

70% 1RM

—

60% 1RM

—

📊 Training Percentage Table

% 1RM	Goal / Zone	Weight	Est. Reps	Intensity

🔬 Formula Comparison — All 7 Estimates

🔄 Rep Range Estimator

How many reps can you do at each % of your 1RM? (Using Brzycki formula)

What is One Rep Max (1RM)?

Your one rep max (1RM) is the maximum amount of weight you can lift for a single repetition of an exercise with proper form. It is the gold standard of maximal strength and the foundation of most serious strength training programs.

Testing your true 1RM is risky — especially for beginners. Instead, you can safely estimate your 1RM by lifting a submaximal weight for multiple reps, then applying one of several validated formulas.

The 7 Formulas

Epley: 1RM = w × (1 + r/30) Brzycki: 1RM = w × 36 / (37 - r) Lander: 1RM = 100w / (101.3 - 2.67123 × r) Lombardi: 1RM = w × r^0.10 Mayhew: 1RM = 100w / (52.2 + 41.9 × e^(-0.055 × r)) O'Conner: 1RM = w × (1 + 0.025 × r) Wathan: 1RM = 100w / (48.8 + 53.8 × e^(-0.075 × r)) w = weight lifted (kg/lbs), r = reps performed

Training Percentage Guidelines

💥

90–100% (Max Strength)

1–3 reps. Pure maximal strength development. High CNS demand. Reserve for peaking phases.

🔥

80–89% (Strength)

3–6 reps. Classic strength zone. Core of powerlifting and strength programs.

💪

70–79% (Hypertrophy)

6–12 reps. Optimal for muscle size. Sweet spot for most bodybuilding programs.

🏃

50–65% (Endurance)

15–20+ reps. Builds muscular endurance and conditioning. Used in circuit training.

Frequently Asked Questions

How accurate are 1RM estimation formulas?

1RM formulas are most accurate for sets of 3–10 reps. For 1–3 rep sets, accuracy is very high (within 2–5%). For sets of 10+ reps, accuracy decreases because high-rep performance depends heavily on muscular endurance, not just maximal strength. Using the average of multiple formulas reduces error. For best results, use a set of 3–8 reps to estimate.

Should I ever test my actual 1RM?

Actual 1RM testing is appropriate for experienced lifters (2+ years of training) who have mastered technique. It carries injury risk and requires thorough warm-up, a spotter, and ideal conditions. Beginners and intermediate lifters are better served by estimating from submaximal sets. Competitive powerlifters and Olympic weightlifters test or perform 1RM attempts during competition.

What is RPE and how does it relate to 1RM?

RPE (Rate of Perceived Exertion) on a 1–10 scale is increasingly used alongside 1RM percentages in modern strength training. An RPE 10 = maximum effort (1RM). RPE 9 = 1 rep left in the tank. RPE 8 = 2 reps left. This helps lifters autoregulate intensity based on daily readiness, rather than relying solely on fixed percentages.

Why does the Epley formula give different results than Brzycki?

Each formula was derived from different populations and methods. The Epley formula tends to give slightly higher 1RM estimates for higher-rep sets. Brzycki is more conservative and often preferred for sets of 1–10 reps. The differences are usually small (within 3–5%). Our calculator shows all 7 and highlights the average, which is the most reliable estimate across different lifters.

Related Fitness & Health Calculators

🔥

Calories Burned Calculator

30+ activities with MET values

Lean Body Mass Calculator

LBM by Boer, James & Hume