# Slider graduations - how many pixels?

I've been asked to create a design which uses sliders to allow the user to enter numerical values. Although (in my view) these are not appropriate, unfortunately my arguments for alternatives have been in vain! I'm therefore looking to understand if any research has been done to establish what a reasonable minimum slider gradiant is. So on a screen with (say) 800px width, how many px should be between each slider position? I'm not aware of any research in this area, and would appreciate being pointed in the direction of anything or hearing other people's experiences

• About how precise do you need to be? What are reasonable min/max levels? – Ben Brocka Oct 26 '12 at 15:39
• Ben - that's kind of my point about not using sliders - unfortunately I've been more or less told to. The question is about how many pixels is reasonable for a single slider movement rather than what each movement needs. Assume it's an able-bodied person with no movement impairment, to simplify matters. – Peter Oct 26 '12 at 16:38
• I recognize the constraint, but those factors are still important for deciding how you design the slider tself – Ben Brocka Oct 26 '12 at 18:10
• Do you have any constraints on the number at all, eg. between 0 and some upper bound, or is it completely open? Even if it is completely open, is there some commonly-used range? (You could, in theory, have a non-linear slider that goes from 0 to infinity or -inf to +inf, but that may not be usable. But could actually appropriate for some scientific domains...) – BrendanMcK Oct 26 '12 at 21:11
• Part of my reason for asking is to get more arguments against doing this (besides the motor control issues, lack of precision, ease of data entry and screen clutter arguments!). I have about 400px to display sliders. One of the values I've been asked to capture is a sum of money, which can be up to 100k. At 1px per unit, that's \$250 per pixel. BUT: 1px is too small, and if I can present evidence that the smallest reasonable slider movement is, say, 10px, then a single movement becomes \$2500 - which may help to change the approach. – Peter Oct 27 '12 at 18:31

Sliders are bad for precision over a large range, but great for getting in the right ball-park. Spinboxes are great for precision, but bad for making big changes. Would it be an option to combine a splitter and a spinbox? That way, you can use the slider to get in the right range, and the spinbox to fine-tune the selected value.