Try C1: =MOD(NOW(),1)-B1

you don't need D2 then

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HTH

Bob

"Dgwood90" wrote in message
...
I need to have a formula that will show how much battery run time I left.
A1 is Battery run time = 40.5 hours
B1 is time batteries started = 12:55 AM
C1 is time on batteries, =NOW()-B2
D2 will be the battery run time left.

I have tried formatting in several different modes, always coming up
wrong.