This is where the idea for this tool came from. There was only a linear scale drawn. To be able to start planning how the apartment is to be finished, we first had to know the scale of the project. With a ruler in hand and our tool knowing the scale of the project is very simple. And once we know the scale, we can easily change the real one dimensions and try to place them on the project.
If we are building a model of a ship, plane or other thing, we can use our calculator, to know the dimensions to scale. Knowing the scale and the actual size, we will quickly know what length the next part should be. More importantly, we can give dimensions, for example in meters, and read them in millimeters.
Distance on the map
This is probably the simplest example you can think of. We have a map with a given scale and we want to know what it is the distance from point A to point B. We measure, enter the data in the appropriate fields and in a fraction of a second we know the result.