No factor is needed:

say a1 contains 8:50 and a2 contains 3:10 and the formula in a3 is:
=A1-A2

the value 5:40 will be displayed, but if you change the formatting of a3 to
General, then 5.666666667 will be displayed and can be used directly to be
multiplied by a rate.

--
Gary's Student


"matelodave" wrote:

I want to enter a start time and end time to show number of hour & minutes
spent against a task(done that) then I want to enter an hourly rate and
calculate the cost but I cant find a formula or calculation that converts the
time hours mins into a decimal (eg 5hr 40min = 5.66) to do the time/cost
calculation.