The linear expression in After Effects is extremely useful. Use it to relate an input to an output value based on proportions. The linear expression is written:

linear(var, varmin, varmax, value1, value2);

You choose a variable and denote the minimum and maximum values. Then, you relate that to value 1 and 2 of your selected value. It’s a great way to relate things that don’t use the same value scale.

It’s easier to learn about this great expression by watching it in action. In this video tutorial, we’ll create two linear expressions to facilitate animation of a bar graph. One expression will help the bar graph resize based on an input value. Another expression will position a text layer on top of the bar graph, no matter how tall the bar graph grows or shrinks.