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For how long should alerts be displayed? By alert I mean messages such as "You are now logged out." in this page:

enter image description here

Normally, they disappear when the user clicks on some link and the page reloads, but this is a single-page-application, the page never reloads (unless the user decides to do so manually).

So, for how long should it be displayed? Any amount of time feels both very short and very long. Leaving it forever (until the user closes it) might not be a good idea either.

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  • Why not keep it up?
    – R. Barzell
    Oct 16, 2015 at 15:53
  • @R.Barzell it gets annoying to have to dismiss it and I'm afraid some users that are not very computer savvy won't dismiss them at all causing their user experience of my app to be very bad.
    – pupeno
    Oct 16, 2015 at 15:57
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    True, but if the alert isn't modal, what harm is there? Also, you can get rid of the alert on a click, even in a single page application. If the alert shows up in a div, you can include clearing the div as part of the click events on your page.
    – R. Barzell
    Oct 16, 2015 at 15:59
  • @R.Barzell the harm is that it takes part of the screen real state and as alerts are added they can take the whole screen.
    – pupeno
    Oct 18, 2015 at 13:40

3 Answers 3

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It varies, but for English language....

Generally the time taken to read a flash notice will vary according to the complexity of the information, length of notice, and focus/distraction level of the user.

That said, I tend to use the following informed approach:

1. Flash notices should be short

  • If a notice is longer than about 1.5 lines, it likely too long for an auto-dismiss. In these cases, re-examine the content and determine whether you want to show it modally (e.g. in a dialog which the user manually dismisses) or via screen change (e.g. take the user to a new page containing the information)

2. I generally use the following formula:

enter image description here

  • This isn't an exact science, but it's worked for me and it's reasonably supported by ergonomic data...

  • Roughly, the logic is:

    • Show animation of 200-400ms is roughly consistent with the saccade time for the eye to refocus on a new place onscreen.
    • Show duration of 50ms x # of characters is roughly consistent with user reading speed. The average English language reader will read about 250-300 words per minute, with an average of 5.8 characters per word (including spaces). At a "safe" estimate for a notice of 200wpm, that yields about 1 character every 50 milliseconds.
    • I apply a 2000ms minimum to allow the user time to congitively context-switch even for short notices, and a 7000ms maximum because I've found that tests about right for the threshold upon which the notice really should not be a flash-based notice (see point #1 above).

  • Fade animation of 700-200ms. The fade animation is slower than the show animation because it gives times for users to finish reading or act (e.g. click to prevent dismissal) if they aren't done yet. Users feel very frustrated if they are halfway through reading something and it disappears suddenly before they can do anything about it.

You will have to adapt this to fit your specific situation, but the general framework may be helpful.

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  • totally awesome...
    – Fattie
    Oct 16, 2015 at 22:17
  • I'm marking this answer as the accepted answer due to the level of detail. In my app, I ended up keeping track of when users interact with the page (something that I wanted to avoid initially) and if certain time has passed and the user is interacting with the app, the alert goes away automatically.
    – pupeno
    Oct 18, 2015 at 13:43
  • Hi, could you please elaborate on the logic of the formula? This is what I got but no matter the length of the copy I get always the same result: =MAX(MIN(LEN("Page published The Page has been successfully published to the platform")*50,2000),7000)
    – Taritaro
    Feb 16 at 14:26
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There is no General rule for Alert display time before hiding it. The case Vary from case to case.

10-15 sec is good for understanding the message or reason of Alert Notification.

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Does your user actually need this alert? What does their persona say? If he's the impatient type who fires and forgets, he's not going to stick around to see if the log off worked or not; he certainly does not need the alert. On the other hand, if she's an auditor, then she may want this alert to last forever, and she maybe even wants a link to a report of past alerts.

Given that the name on your web page includes the word "ninja", I'm suspecting that your users are closer to the first type, and don't actually need the alerts.

When you're struggling to answer a design question, look around for alternatives that make things simpler.

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