tables - How should times be aligned in a column

I have a data grid of three columns of type [Time, Decimal, Decimal]. All records in the decimal columns have the same number of decimal places. I have right aligned these as they're numeric.

But I don't know what the convention for time alignment is. I've had a search online for suggestions but it seems like there isn't one convention. I wonder if this is related to the fact that date and time format vary significantly between locales.

Is there a convention for times? And if not, does it seems reasonable to also right align it in my case, as left aligning looks asymmetric and ugly given the two succeeding columns are right aligned.

Here is an example:

| The Time | Some decimal | Another decimal |
|    14:02 |      12.5456 |        565.4735 |
|    14:06 |      12.1043 |        568.8763 |

Or

| The Time | Some decimal | Another decimal |
| 14:02    |      12.5456 |        565.4735 |
| 14:06    |      12.1043 |        568.8763 |

Note that my font is NOT fixed width. The example above is purely to illustrate the structure of my data grid.

Answer

Right align

Yes, it is reasonable to right align in your case. For other date and time formats, the alignment can be discussed.

Example from Spotify:

The biggest number can vary in number of figures -- in your case the hour, in this example the minute -- but the smallest cannot.

So right alignment is a simple way to a keep a consistent scale along the Y axis, that is keeping the colon at the same place, no matter the time displayed. This way the value of a figure can be directly compared to the value of a figure immediately above or below it.

Thoughts

Yes, the format varies from culture to culture. What to seek for, no matter what the figure represents (time, money, percentage, love) is always to align figures of the same weight. Normally this is the same as aligning the colon or decimal sign. Which is the same as right aligning a time value, like ´HH:mm´, as it has the convenience of having a fixed number of digits to the right.

This method does not work in all date formats though. Using the international standard, the fourteenth of March this year is written 2012-03-14. The weight of the figures will be consistent in the Y axis no matter the alignment, for the next eight millennia. But in several cultures zeros are omitted both here and there, for example writing the same date (pie day) can be written 14/3/2012. If not padded with zeros, the Y axis consistency of these formats is lost many times every year, no matter the alignment.

Stripping the biggest number from the occasionally initial zero is still a good idea, for the left most time unit. Have a look at the songs in the list. Without even reading the numbers you can immediately spot that one is longer than the others. Using four digits for representing duration (or time) would require some extra milliseconds and cognitive load to actually read and compare the value of those figures.

Summary

Reduce cognitive load by

1. 
   

   aligning figures of the same weight, which often means right align, and

   
   


2. 
   
   

   removing occassional left most initial zeros.