How many pockets do I need in an expanding file organizer?

For general home filing, 7–13 pockets is usually enough. Choose 21 pockets if you want A–Z alphabetic filing for clients, invoices, or correspondence, and 31 pockets if you're filing by day of the month (common in bookkeeping, legal, and tax workflows). More pockets isn't better if you don't have a sorting scheme that needs them.