What does this calculator work out?
It lays the fee on a single spot trade side by side across four cases: no discount, BNB deduction only (25% off spot fees), a 20% referral rebate only, and both together. When they stack, the fee is charged with the BNB discount first, then the rebate takes 20% of that discounted amount, which is the order Binance actually settles in. It works out the trading fee itself and does not include the bid-ask spread or slippage, which depend on market depth at the moment you buy. Every calculation runs locally in your browser; the page collects nothing and uploads none of what you type.
Two reminders. The BNB discount needs BNB held in your spot account with the toggle switched on in settings. The referral rebate is not taken off when you place an order but returned to your account on a cycle, with the timing set out on Binance's fee page and referral page. If you do not have a referral code yet, sign up with our BN03688 to get the 20% discount (actual rate as shown on the sign-up page).
To understand the fee structure itself, how VIP tiers are split, where futures fees differ from spot, and how withdrawal fees work, read Binance Fees Explained.