In Dutch, we have the word "kwartier" to denote a 15-minute period. It is derived from the word "kwart", which means quarter. It is very common to use this word in both spoken and written language.

Is there a similar word or expression in English (e.g. quarter)? And is it very common to use this word, or is it more commonplace to use expressions such as quarter of an hour, 15 minutes, etc.?

The scenario I'm considering in particular is that of labels on forms or in software. The 'user' has to indicate how much time was spent on something, in time units of 15 minutes. What would be the most appropriate way:

• Time spent: # quarters
• Time spent: # quarters of an hour
• Time spent: # times 15 minutes
• Time spent: # minutes (in software, make 15-minute increments the only possible way to input the time)
• …