Head gasket volume

I was thinking about the right way to calculate head gasket volume ,

because I thought the gasket has different thicknesses depending if the gasket fitted in between the cylinder head and the block with tighted head studs or when it's just out of the engine ,

so which thickness should I go with my calculation and how to measure the thickness with gasket fitted in the engine

Thanks

It's the compressed thickness of the gasket that you need to use for this calculation. If you're using an aftermarket MLS gasket, the compressed thickness is usually listed.