Why numeric sliders are lazy UX

Is a numeric slider the best interaction model?

I’ve spent the majority of my career leading UX teams working on digital financial products, and too often, I see practitioners revert to using numeric or range sliders for the wrong reasons.

Asking a user to interact with a slider to land on a specific number is a terrible interaction pattern, and on touch screen devices, even more so. Especially when using larger value ranges, the greater the value, the harder it is to select the right number. If you think about it in a financial product where decimal points are in effect, the amount of possible combinations in a $0 — $10 range is equal to 100 possible outcomes. Now on one of the newer touch screen devices, that’s a numeric change about every 3 pixels. It would almost be impossible to select the value you want.

A slider is only good practice when you know the value is a relative quantity, not a numeric value. For example, setting the audio volume or screen brightness to low, medium or high works but not when trying to set a value to 5, 6 or 7.

Sliders are best used when users have direct feedback on the change. Like the changing of the volume or the changing of the brightness. Unless users are incredibly OCD and need to know the numerical value of these changes, the outcome is represented with sound or sight, which allows the user to get the direct feedback they need.

So what do we use instead?

When choosing the interaction model for the input method, consider the value range that needs to be entered. If you can go up in incremental values, then a vertical slider in a sidebar could be a great model. For anything that’s going to have infinite or a high range of values, it’s recommended to simply use an input box. This allows users to simply input the numbers they want using the numerical keypad.