:format as hours only 1 decimal

I want to calculate the time between two dates. I tried end-start:formated as hours, but this only gives 1 decimal.
For example: 18:00 till 18:45 gives 0.8

I fixed it with using :formated as minutes /60 but this is laggy sometimes. Does someone know a stable way to do this

thanks!

Depends what you are trying to display but this post explains how to find the duration between dates.