1RM Calculator
Estimate your 1RM (One Rep Max) safely by inputting weight and repetitions, and check the training percentage table.
Usage Tips
Plan your training weight without testing your true max
For lifts like the squat, bench press, and deadlift, testing a true one-rep max can be risky or tiring. Enter a weight you can lift for multiple reps to estimate your 1RM, then use the percentage table to plan strength, hypertrophy, or volume-based training sets.
What is 1RM Calculator?
The 1RM Calculator estimates your One Repetition Maximum—the absolute maximum weight you can lift for a single rep with proper form—based on a sub-maximal performance (weight and repetitions). By removing the high physical risk of injury associated with true max-out attempts, this tool provides a safe estimation. It also generates an intensity percentage-based training table (100% to 50%) aligned with specific workout goals (strength, hypertrophy, or muscular endurance).
How to Use
- 1Enter a weight you can currently lift with correct form and specify the maximum number of successful repetitions (reps). (A range of 3 to 10 reps yields the highest accuracy)
- 2Choose the measurement unit (kilograms [kg] or pounds [lbs]) to match your training environment.
- 3Review the estimated 1RM calculated from the average of peer-reviewed formulas (Epley and Brzycki equations).
- 4Reference the intensity breakdown table (100% to 50%) to structure your sets for maximum strength (85%+), hypertrophy (70-80%), or muscular endurance (under 60%).
- 5Copy the estimated 1RM results and target weight table to log in your fitness journal or training application.
Average Epley and Brzycki estimates before using training percentages
Last reviewed: July 11, 2026Estimated 1RM formulas
Epley = weight × (1 + reps ÷ 30); Brzycki = weight × 36 ÷ (37 − reps); 1RM = (Epley + Brzycki) ÷ 2
The calculator estimates a one-repetition maximum from a submaximal set, then derives percentage-based training loads.
A 100kg set of five repetitions
- • Load 100kg
- • 5 repetitions
- • Check the 90% training load
- 1. Epley = 100 × (1 + 5 ÷ 30) = 116.67kg
- 2. Brzycki = 100 × 36 ÷ 32 = 112.50kg; average 1RM = 114.58kg
- 3. 90% load = 114.58 × 0.9 = 103.13kg
Estimated 1RM is about 114.6kg, making the 90% training load about 103.1kg.
How to read the result
- A controlled set of roughly 3–10 reps usually gives a more useful estimate than a very high-repetition set.
- The 50–100% table is a starting reference and does not replace readiness or coaching on the day.
Conditions that change the result
- Above 12 repetitions, cardiovascular fatigue and technique can contribute more error to the estimate.
- An estimated 1RM is not a safely tested maximum and cannot remove injury risk.
Common input mistakes
- Counting assisted or momentum-driven repetitions as strict repetitions can inflate the result.
- Do not turn the calculated maximum into an immediate working load without a proper warm-up.
Reference Knowledge
- ●Epley Equation: 1RM = Weight × (1 + Reps / 30) (Highly reliable for moderate repetition ranges)
- ●Brzycki Equation: 1RM = Weight × 36 / (37 - Reps) (Known for superior accuracy with lower rep counts under 10)
- ●Averaged Estimation Model: To mitigate outlier variances and present realistic metrics, this tool uses the arithmetic mean of both formulas as the baseline projection.
- ●Repetition Threshold limits: As reps exceed 12, physical variables like lactic acid buildup and aerobic capacity begin to distort calculations. For the most accurate strength projection, use input data from sets that reach failure between 3 to 10 repetitions.
FAQ
Q.Should I perform a direct 1RM test or use this calculator?
Direct 1RM testing places extreme mechanical stress on your musculoskeletal system, raising the risk of severe injury. Unless you are an advanced lifter with professional spotters and safety racks, utilizing a sub-maximal estimation via this calculator is highly recommended for longevity and safety.
Q.What repetition number gives the highest accuracy for 1RM estimation?
Aim for a repetition range between 3 and 8 reps to failure. Using high-rep data (e.g., 15 or 20 reps) introduces muscular endurance and cardiovascular fatigue variables, which usually leads to an underestimation of your true raw power.
Q.Are there different 1RM formulas for men and women?
The core mathematical equations (Epley and Brzycki) do not change based on sex or age, as they calculate purely mechanical work output. However, since central nervous system efficiency and muscle fiber composition vary, treat the percentage table as a starting benchmark and adjust based on biofeedback.
Q.How should I apply the intensity percentages to my training splits?
For maximal strength development, target 80-90% of your 1RM for low-rep ranges (1-5 reps). For muscle hypertrophy, lift at 70-80% intensity for moderate ranges (6-12 reps). For muscle endurance, perform sets at 50-60% of your 1RM for high reps (15+).
