How should I round a countdown?

Question

I have an overlay for a livestream on which I want to display a countdown until some specified time, but without precision. Because the time doesn't correlate exactly with what is being counted down to (+-3 minutes), I don't really want to give a resolution of 1 minute because that makes it seem more precise than it really is. The timeframe that it is counting over would be about an hour, so just showing hours wouldn't make sense, so I would like to show the countdown in increments of 5 minutes.

This leaves me with the question of how to round to a multiple of 5.

If I round up, then at 5.1 minutes left, the audience still sees 10 minutes, which is misleading

If I round down, then at 9.9 minutes left, the audience sees 5 minutes, which is better than the previous case, but still misleading

The third option is to round to the nearest multiple, up or down, but then it transitions from 10 minutes to 5 minutes at some odd time (11:52:30), as the timer is counting down to a published time (say 12:00)

Of these three rounding options, which makes the most sense/is clearest to the audience? Alternatively, is there another way to do a countdown without this rounding that makes it clear that the end time isn't exact?

Answer 1

If you want to display time without precision, I think you will need to use actual words instead of __:__:__, because that format gives the impression of precision.

For example, if you want to count down every 5 mins, you can use "less than".

Example:

• Less than 1 hour left
• Less than 55 min left
• Less than 50 min left
• Less than 45 min left
• ...
• Less than 5 min left

You might be able to shorten it using "<" sign, but you should test this with your users.

Example:

• <1 hour left
• <55 min left
• <50 min left
• <45 min left
• ...
• <5 min left