The steps are: collect positions and cash balances from every custodian, exchange and broker; price each position using the sources set out in the valuation policy; convert to the fund's base currency; accrue management fees, performance fees and expenses; deduct liabilities; and divide by the shares in issue, class by class. The administrator then reconciles the result against the manager's own records before publishing.
Errors in NAV calculation are the most common operational failure allocators worry about, which is why independence of the calculating agent and a documented pricing policy are standard due-diligence questions.