Yvette's Performance Pizza is a small restaurant in Detroit that sells gluten-free pizzas. Yvette's very tiny kitchen has barely enough room for the three ovens in which her workers bake the pizzas. Yvette signed a lease obligating her to pay the rent for the three ovens for the next year. Because of this, and because Yvette's kitchen cannot fit more than three ovens, Yvette cannot change the number of ovens she uses in her production of pizzas in the short run.

However, Yvette's decision regarding how many workers to use can vary from week to week because her workers tend to be students. Each Monday, Yvette lets them know how many workers she needs for each day of the week. In the short run, these workers are inputs, and the ovens are inputs.

Inputs that can't be changed in short run are fixed inputs, as well as costs of acquiring them. These inputs stay the same in quantity and cost, no matter how many outputs are created. On the other hand, those inputs that can be changed in the short run are variable inputs, as well as expenses of acquiring them. They change in the short run with the changes in produced output.