Need help on refill conversion calculator

Hi , I received an email from pyramid air on an air venturie 90 ci 4500 psi carbon fiber refill tank for my pcp . I have the new condor SS with the 500cc tank . I know there are conversion calculators to figure this out but when I go to them it says in ft not ci . I do not know what a 90 ci tank relates to in ft. Does anyone know how many refills I can get with a 90ci 4500psi tank to fill my 500cc tank from 2000psi to 3000psi ? Thank you