tables - How to display duration (HH:MM) so it isn't confused with clock time

I have a table in my application that shows dates along its x-axis, and different statuses along its y-axis. The table keeps track of how much time an employee spent in a given work status (on duty, off duty, etc) for the given day in hours:minutes. I've included a rough sketch below:

My worry is that some users may get confused and think that this time represents something different, such as the time at which this state occurred (i.e. went on duty at 6:00, went off-duty at 18:00). Is there a better way to represent this time to be more clear of what it is representing, or is this just something that users will have to learn on their own using my software over time?

Answer

You are right to ask this question. It really depends on who your users are.

In labor-intensive environments, users are often very familiar with the HH:MM notation for duration, so it's OK to use that format. But, I agree that even for those environments easy to get it confused with time.

Is there a better way?

Let's start with the existing solution. The benefits of HH:MM are:

• It's universally recognized as a time format


• It's scannable, i.e. when you have lots of data in a grid, the HH:MM aligns nicely so it's easy to scan.

With this in mind, here are two approaches. You could label the existing table to remind users that it's showing duration rather than time. Or you could adopt a different notation to indicate that it's duration:

The notation on the left is popular these days, and preserves some (but not all) the scannability while denoting duration more clearly. The approach on the right keeps the cleanliness of the HH:MM notation, and sets user context elegantly by utilizing the top-left corner (which is the visual entry-point to the table anyway).