One Rep Max Calculator

Use this simple one rep max calculator tool to work out an estimate for your rep maxes. The tool uses the popular Brzycki formula to work out an estimate of your one rep max.

Note: Everybody is different so these are only an estimate for you to use to help your programming. The lower your rep input, the more accurate the calculations tend to be.

Input your numbers into the calculator below then scroll down for more information on using your one rep max..

One Rep Max Percentage Chart

Some programs work with different percentages of your one rep max. The chart below presents an estimate for the percentage based on the amount of reps you are able to perform.

For example, if you are able to perform 5 reps with a given weight, the chart tells you that weight is around 87% of your one rep max.

You can also combine your one rep max from the calculator with the chart below to find predicted maxes for other rep ranges.

For example, the chart below estimates your five rep max to be 87% of your single max. So, you would find your five rep max by multiplying your one rep max by 0.87.

Reps Performed

Percentage of 1RM





















How to Test Your One Rep Max

Thanks to the rep max calculator and percentage chart above, you don't always need to test your true one rep max every time you want to begin a new program.

However, there are times when you will want to test it out since the above calculations are unlikely to be exact. It's also nice to see what you can do from time to time as a gauge of overall progress.

Testing a true one rep max is intense and should only be done once you have mastered the technique of a given exercise.

A common question when testing maxes is "how to work up to a one rep max without fatiguing yourself?"

The chart below is the way I have always done it and it seems to work well. Of course, you may adjust the rest periods depending on how you feel but it is a good guide. To use it, you will need to have a rough idea of your one rep max or at least a realistic goal to work from.

One rep max testing procedure:

Percentages are based off of your predicted or target one rep max

Set 1 - 30% for 5 reps
Rest 1 min
Set 2 - 50% for 5 reps
Rest 1 min
Set 3 - 60% for 3 reps
Rest 2 mins
Set 4 - 75% for 2 reps
Rest 3 mins
Set 5 - 90% for 1 rep
Rest 5 mins
Set 6 - 100% test for new PR

If the last set feels good, rest again for 5 minutes, increase the weight slightly and try again. Only increase the weight if your technique holds up well.

The percentages are just a rough guide and will usually be rounded up or down slightly based on plate increments. For example, if 90% came out to 101 kg, I would select either 100 kg or 102.5 kg.

Prilepin's Table

An effective and fairly simple way to use the information gathered from your one rep max calculator and the percentages is to use this table, which was created by Soviet sports scientist A.S. Prilepin as a result of his studies of over 1000 weightlifting champion's training logs.

The chart is used to calculate the number of total reps you will need to do in a single workout with a given percentage of your one rep max in order to stimulate a positive training response.

The original data was collected from weightlifters but it can be used and applied to powerlifting and general strength building.

To learn how you can properly apply the chart to powerlifting, check out this article from

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