One Rep Max Calculator
Estimate your one-rep max using the weight lifted and number of repetitions completed.
Calculate One-Rep Max
Enter weight and reps to estimate your one-rep max.
Formula
This calculator uses the Epley formula, commonly used in strength training and powerlifting.
What is One-Rep Max?
Your one-rep max (1RM) is the maximum amount of weight you can lift for a single repetition of an exercise.
Why athletes use 1RM
Strength athletes and coaches use 1RM estimates to measure progress, structure training blocks, and determine percentages for workouts.
Training insight
Most people test strength too often. Quietly, consistent submaximal training usually builds strength faster over time.
For many lifters, sets of 3–6 repetitions provide a useful balance between strength development and one-rep max prediction accuracy. This rep range allows you to train with heavy loads while still accumulating enough volume to build strength over time.
You may also find our TDEE Calculator or Boxing Calorie Calculator useful.
Frequently Asked Questions
How accurate is a 1RM calculator?
A one-rep max calculator provides an estimate of your maximum strength based on the weight lifted and the number of repetitions completed. It is generally most accurate when using lower rep ranges, but actual results can vary between individuals.
What rep range works best for estimating a 1RM?
Most one-rep max formulas are most reliable when based on sets of 1 to 10 repetitions. Accuracy tends to decrease as repetition counts become higher because fatigue has a greater impact on performance.
Should beginners test true one-rep max lifts?
Most beginners benefit more from estimated one-rep max calculations than attempting true maximum lifts. Using a calculator can reduce injury risk while still providing useful strength data for training.
Why is knowing your one-rep max useful?
A one-rep max estimate can help you select appropriate training weights, track strength progress, and build structured strength programs. Many training plans use percentages of a one-rep max to prescribe workloads.
Can I use a 1RM calculator for any exercise?
Yes. One-rep max calculators can be used for exercises such as the bench press, squat, deadlift, overhead press, and many other resistance training movements.
What is a good one-rep max?
There is no universal "good" one-rep max because strength levels vary by age, body weight, training experience, and exercise selection. The most useful comparison is your own progress over time.