Simple Guide To Progress Bar Correctness

2015.08.20   prev     next

ONE of my biggest pet peeves? Progress bars that don’t really measure progress. Use this simple guide to understand how progress bars are supposed to work, and how they’re not supposed to work:

Ideal:

• When the user clicks a button that requests a time-consuming action (on which the user must wait), the progress bar appears immediately.
• Before it makes any progress, the bar is briefly visible in its 0%-full state.
• The bar makes smooth, steady progress from 0% to 100%.
• Just before it disappears, the bar is briefly visible in its 100%-full state.
• When the bar reaches 100%, it quickly disappears, the requested action is finished, and the computer is immediately ready for the user to choose the next action.

Not ideal, but OK:

• The bar makes not-so-smooth, somewhat jerky progress toward completion.
• The bar displays as a barber-pole animation, or otherwise indicates activity without even pretending to indicate how close the task is to completion.

Not OK at all:

• After the user clicks the button that requests the time-consuming action, there’s a noticeable pause (not to mention a long one) before the progress bar appears.
• The bar appears, but there’s a big pause before it starts making progress toward com­ple­tion.
• The bar appears with significant progress already filled-in.
• The bar stalls part-way to completion with a long pause.
• The bar gets slower and slower as it nears completion (or as it nears some arbitrary point, such as 2/3 completion).
• The bar abruptly completes at an arbitrary, unpredictable time, when it looked like it could have taken many seconds longer.
• The bar disappears before the user ever gets to see it in a fully completed state.
• The bar restarts one or more times.
• The bar completes and/or disappears, but then there is a long pause before the user can choose the next action.

Bottom line? Progress bars should never deceive. They should be as accurate as possible a measure of the time between the user requesting the action and the computer being done with that action and ready for the user’s next request.

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