Hi,

Here are some formula to create the effect.
A1: =50 (or whatever your summed value is

B1: =Green C1: =IF(AND(A1=75,A1<=100),A1,0)
B2: =Yellow C2: =IF(AND(A1=50,A1<75),A1,0)
B3: =Red C3: =IF(AND(A1=1,A1<50),A1,0)
B4: =White C4: =100-SUM(C1:C3)

Select the range B1:C4 and create a pie chart. Colour the slices to
match the slice names. Adjusting the value in A1 will adjust the share
of the 2 visible slices with the colours matching your value bands.

For a more gauge looking pie chart have a look at Jon Peltier's example.
http://peltiertech.com/Excel/Charts/SpeedometerXP.html

For a more gauge looking xy chart have a look here
http://www.andypope.info/charts/gauge.htm

Cheers
Andy

Patrick wrote:
I hope this is a simple question. How do I get a pie chart to begin at 100%
availability and decrease based on a sum at the end of a column of values? If
I can color it, ie. 100%-75% green 74%-50% yellow, and 49% or less as red,
that would be even better. The only thing I can relate it to is an
automobile's gas gauge.

--

Andy Pope, Microsoft MVP - Excel
http://www.andypope.info