Logarithmic Sliders

Here’s a nice UI feature I noticed in Procreate, an iPad painting app: a slider control with variable increments. The app has a couple of these slider controls to manage the size and the opacity of the brush, but instead of using equal increments from 1 to 100, they use a weighted system, spacing them further out at the lower end of the range.

Here’s my aproximation of the values the slider uses:

As you can see, going up about a fifth up the slider only gets us to about size/strength 5 (out of 100). Just under half the slider goes to 20, and then it speeds up all the way to 100. This is likely based on a logarithmic scale and works great, especially for picking those tiny brushes sized 1 to 5, which would be extremely fiddly if every couple of pixels made a difference. Of course the values at the higher end are harder to pick, but in the context of the app they don’t matter as much: when you want a large brush you just want a large brush, precision doesn’t matter here.