Not 100% sure what you're asking - do you want to input times onto your spreadsheet in HH:MM format and then convert these to decimal time with a formula, e.g where 12:30 ( 12 Hrs 30 Minutes ) is the input value, which then needs to be converted to 12.5 ( twelve and a half ) hours ?
If so make sure the cell ( e.g. A1 ) containing the HH:MM data is formatted as a time cell, then use the formula =HOUR(A1)+MINUTE(A1)/60 to convert to decimal hours.
Hope this is what you wanted.
