1 Rep Max Calculator
Estimate how much you can lift for a single rep
1 Rep Max Calculator
Enter weight in Lbs or Kg (result will match).
Number of clean reps (recommended: 1-10).
Our free 1 Rep Max Calculator uses proven formulas (Epley and Brzycki) to estimate your maximum strength based on lighter lifts. Knowing your 1RM is essential for strength training programs that prescribe percentages.
How to Use This 1 Rep Max Calculator
- 1Enter the weight you lifted.
- 2Enter the number of repetitions you completed.
- 3Click Calculate to see your estimated 1 Rep Max.
- 4Use the percentage table to plan your workouts.
Understanding Your Results
The result is an estimate of the maximum weight you could lift for one repetition with good form. Use the provided percentage breakdown (e.g., 85% of 1RM for 5 reps) to structure your training cycles.
Frequently Asked Questions
Your One Rep Max (1RM) is the maximum weight you can lift for a single, properly executed rep. It is a key metric for strength and power. It is calculated either by testing directly in the gym or by estimating using a sub-maximal lift (e.g., 5 reps) and a formula like Epley or Brzycki.
Most strength programs prescribe sets based on percentages of your 1RM (e.g., 'Do 3 sets of 5 reps at 85%'). Calculating your 1RM allows you to train effectively in the correct intensity zone without constantly maxing out, which is safer and prevents burnout.
Absolutely. Testing a true 1RM involves lifting very heavy loads to failure, which carries a high risk of injury, especially without spotters. Using a calculator allows you to estimate your max from a safer, lighter set (e.g., 5-8 reps), reducing injury risk while maintaining 95% accuracy.
Strength standards vary by exercise and experience. For an intermediate 180lb male, a 1.25x bodyweight bench press (~225 lbs), 1.5x squat (~270 lbs), and 2.0x deadlift (~360 lbs) are often cited benchmarks. For females, 0.75x bench, 1.0x squat, and 1.25x deadlift are common targets.
Formulas like Epley and Brzycki are most accurate for lower rep ranges (1-10 reps). Once you exceed 10 reps (e.g., a set of 20), muscular endurance plays a larger role than strength, making 1RM predictions less reliable.
The Epley formula (Weight × (1 + Reps/30)) is slightly more aggressive and accurate for low reps. The Brzycki formula (Weight / (1.0278 - 0.0278 × Reps)) is a bit more conservative. Both are widely accepted in strength and conditioning.
Beginners can re-test or re-calculate every 4-8 weeks as they make rapid 'newbie gains'. Advanced lifters might only test true maxes every 12-16 weeks (at the end of a training block/peaking cycle) to avoid excessive central nervous system fatigue.
Yes, calculation is perfect for beginners because their technique often breaks down under maximal loads. Beginners should stick to estimating their max from sets of 5-8 reps to prioritize safety and form learning.
For hypertrophy (muscle growth), the 'sweet spot' is often considered 65-80% of your 1RM for sets of 8-12 reps. This provides enough tension and metabolic stress to stimulate growth without excessive joint strain.
To increase strength, follow the principle of Progressive Overload: gradually add weight, reps, or sets over time. Focus on compound movements (Squat, Bench, Deadlift), prioritize technique, and allow for adequate recovery and deload weeks.