A lot depends on the brand of paint, and type of spray equipment you're using.
PPG's Omni line of base colors, typically takes 1 and a half times more color then their DBU line.
Plus if you're using a "syphon" style spray gun... you will need to factor another 10-15% for atomized color that goes into the atmosphere(aka overspray
Normally for me to paint a complete car.. including partial jambs.
I'll use 2 qts. base, and 3-4 quarts clear.
You really should have at least 3 mils of clear after cutting and buffing
I'll normally end up with a pint or two of un-reduced base, and as much as a quart un uncatalyzed clear left over.
But that's with my SATA Jet 95 gravity feed gun.
A syphon spray gun would need more material.
A safe bet would be a quart of base, and appropriate reducer.
2 qts. clear, plus catalyst, and reducer.