Is your backpack too heavy for you? New data from the Uni High Statistics class suggests that while many Uni students’ backpacks are light enough to be called healthy, some students should be carrying significantly less.

According to the University of Pittsburgh Medical Center, a backpack should not weigh more than 15% of a person’s body weight. If the average highschooler weighs 115 pounds, the average student should carry no more than 17 pounds in their backpack.

A group of students from the Statistics class weighed the backpacks of 60 Uni students across every grade by standing on a scale with each backpack and subtracting their own weight. The average backpack weight was 14.7 pounds, and the standard deviation, a measure of how spread apart the data is, was 3.6. A histogram of the data is shown here.

This data, as is visible from the graph, is normally distributed–in other words, bell-shaped and symmetrical. Using the normal distribution, the Statistics class found that around 73.9% of students carry a healthy weight (17 pounds or less) in their backpacks, according to the average high school weight of 115 pounds.

So, it seems that though most students carry sufficiently light backpacks, many do need to think about carrying less. If you weigh less than 115 pounds, 17 pounds is also too much–and no, strength does not have to do with it. If you carry a lot in your backpack, consider weighing it to see if it is too heavy for you.