ok, im doin a rebuild and need help on figuring my cr! i have a 4.04 bore, 58cc heads, 3.75 stroke (385 ci) and flat top pistons, no valve release, and my piston at tdc is .200 in the hole! so if i could figure out how many cc's .200" with a 4.04 bore is i could use that figure as my valve relief and figure my cr with a certain head gasket thickness. does this make sense? lol!

 

You mean .020 in the hole?

If they are .200 down then you need to be buying more parts because your rotating assembly does not match.

This will help you with compression calculations.
https://www.camaroz28.com/services/calcs/

If you just want to do a little piece of it like you asked then you just need the formula for calculating the volume of a cylinder, basic geometry. The conversion from inches to metric is 1inch = 2.54 centimeters

 

Trusting you can figure out the area in inches, taking that figure and multiply by 16.387. There are 16.387cc in a CI.

Dwayne may have been a bit vague, but is what I stated far removed from what he noted above? To tie the metric 16.387cc figure to 2.54 centimeters figure, cube 2.54 and see what you get.
Maybe it's just me, but... no!

 

Don't take anyones word for it. Simply measure your parts and use a compression ratio calculator such as this one. http://www.csgnetwork.com/compcalc.html