Calculating true net profit on Amazon involves subtracting product sourcing costs, inbound shipping fees, referral fees, FBA fulfillment charges, and storage fees from total sales revenue. You must also account for pay per click advertising spend, return processing costs, and subscription fees to determine net earnings accurately. Using financial tracking software or detailed spreadsheet formulas helps track fluctuating marketplace expenses over time. Knowing your exact profit margin ensures smarter pricing decisions and sustainable business growth.