How does a bench press calculator work?

Most bench press calculators either work with a mathematical formula which you will find in this article or are based on empirical results from a study. Calculators are a good tool to determine general strength, track progress and program an athlete's schedule. Be careful aroundmaximum efforts especially for very strong athletes as physics dictate exponential effort while calculators usually assume linear strength progression. In short, this means the stronger the athlete the more inaccurate the calculators become.

Starting with calculators

When you have been hitting the gym for a considerable amount of time, probably even if you just started out, you have come along calculators. These little excel spreadsheets or websites give you information what your one repetition maximum is based on what you lifted in a certain session. You type in your number of repetitions and sets and then your presumed ultimate strength pops up. I don't know about you, but for me, it was a very satisfying and exciting feeling the first few times I tried one. But what does this magic box actually do?

It depends on which calculator you use and normally you can find the underlying assumptions with which the calculator operates in the footnote of the page. I recommend reading those to really make sure. Calculators usually operate in one of two ways. They either compare you to a group of people which have been tested in an experiment and estimates are given from there or they work with a mathematical formula. Both approaches have their pros and cons.

Maths or tested?

If you are being compared to a certain sample group of people and your one repetition maximum is determined from there it should be questioned how similar this sample is to you. If you are a bench pressing beast who has pecs bigger than someone else's thighs chances are pretty high that the relevant sample group is of little or no relevance to you. Same goes if a bunch of grannies going through rehab have been the subject of the study. Of course, I exaggerating here, but still, I find that this is a good way of driving a point home so that it sticks. The good site of these samples is that the numbers are based on someone going to the gym and lifting some things. Therefore they are usually more relevant to reality, if the sample group has relevance to your body size, age and health record.

The mathematical formula approach is used more widely. It is very likely that one of the bench press calculators you found online works mathematically and not empirically. The big advantage with this approach is that you will always get the same result no matter what you type in. The challenge with this is that it does not accomodate for individual differences based on age, weight, and experience. Take experienced lifters as an example. Just because you can do an 800 pounds deadlift for repetitions (which is a very impressive feat in itself) you do not necessarily have a maximum of a 1000+ pounds.This is due to the law of diminishing returns and physics. The force you need to lift a weight escalates in an exponential way while most calculators work on a linear basis. The resulting discrepancy is smaller for low weights but becomes more significant the more weight is being moved.

Formula being used in many calculators

The formula most often used for calculators is

Weight x Reps x 0.0333 + Weight

I personally find it to be a good estimate to see where I can place a one repetition maximum attempt. If you want to test your one rep max based on this formula approach the first attempt with 90% of what you calculated to be on the safe site. It is generally a good approach to be conservative when testing maximum effort to minimize injury risk. Avoid that your ego will hurt you. As long as you are not in a competition which you can win there is no gain to be had for risking injury.

Conclusion

Bench press calculators are a useful tool to plan your exercises and track your progress. They are worth the time if you know their limitations and use the results sensibly. The only real proof of strength is to successfully complete the lift in real life and not on a piece of paper.