How to display huge sum of hours

Question

I have a table which sums up worked hours for each project. When the ammount of hours is huge, has still sense use hh:mm format, or decimal format could be more clear?

Reading, for example 7650:30, looks (in my personal impression) strange.

+-----------+-------------+
|  PROJECT  | HOURS SPENT |
+-----------+-------------+
| Project 1 |     5640:00 |
| Project 2 |      740:30 |
| Project 3 |      340:00 |
| Project 4 |      110:30 |
| Project 5 |       40:00 |
+-----------+-------------+

OR

+-----------+-------------+
|  PROJECT  | HOURS SPENT |
+-----------+-------------+
| Project 1 |     5640,00 |
| Project 2 |      740,50 |
| Project 3 |      340,00 |
| Project 4 |      110,50 |
| Project 5 |       40,00 |
+-----------+-------------+

Answer 1

You probably see this type of table in a Time Tracking app. Its purpose to track time, so you can understand how much money you do/spend.

In this context hours are like any other resource like money or beer or whatever. You probably don’t need to display minutes at all and round the numbers up.

If you cant round numbers, decimal representation 1.75 is better than 1:45 (1h, 45m) because you can multiply 1.75 * 10$/h and get results right away.

This will make table clear and easier to read. Aligning to the right is the best thing you can do.

Answer 2

Depending on the granularity of the time (the smallest amount of time you can assign to a task) I would suggest the following formats (assuming the granulation is one quarter of an hour):

• the most explicit

  5640h 00'
  740h 30'
  340h 15'

  showing also how many minutes the total includes. And everyone knows that 30 minutes is half an hour (for the financial cost calculation)

• visually descriptive

  5640 h
  740½ h
  340¼ h

  where a fraction (depicting anything between 0 and 1 hours at first glance) is shown in a fraction of a font size

• calculation friendly

  5640.00 h
  740.50 h
  340.25 h

  (or omit the units description for even more "plain" look) is the easiest for quick calculation (copy/paste into a spreadsheet) but the least appealing for the human.

In all cases I'd keep the unit descriptor, even if it is repeating the table header row - it helps to understand that we are still talking about the hours in the table.