hi
excel doesn't have a built in "stopwatch" but a number of people have wanted
such.
see this site.
http://www.mvps.org/dmcritchie/excel/datetime.htm
all about time and dates, how to calculate, measure, extract, ect.
this is a large site but down towards the bottom is a "timer". not sure if
you can use it but it might give you ideas.

Regards
FSt1

"David94" wrote:

I am doing a science fair project which involves human reaction times. Can I
set Excel up to measure and record the time between two inputs (keystrokes,
mouse clicks, etc...). Does Excel have a "stopwatch" function?