Glossary / Buying & exchanges
Bid-ask spread
Also known as Spread.
- Definition
- The bid-ask spread is the gap between the highest price a buyer will pay and the lowest price a seller will accept, and you pay half of it every time you cross.
Two prices exist at all times, never one. The distance between them is the market's charge for immediate execution, and on a deep bitcoin book it is often a dollar or two against a coin worth six figures. Coinbase describes the spread built into its simple trades as roughly 0.50 percent, several hundred times wider, quoted as a single price so you never see the two sides.
How it works
A spread is what market makers charge for standing between buyers and sellers.
Someone has to be willing to buy when you sell and sell when you buy. The firms that do this post a bid slightly below the going rate and an ask slightly above it, and they earn the difference on the round trip. That difference has to cover their inventory risk: if they buy your coins at 99,995 dollars and the market drops before they resell, the spread was their only cushion. Competition drives it down, risk drives it up.
Three forces widen it. Volatility is the first, because a maker facing violent price moves needs a bigger cushion and posts one. Thin volume is the second, which is why a BTC pair against a small national currency quotes a wider spread than the same platform's dollar pair at the same moment. Weekends and holidays are the third, since bank rails close, arbitrage between venues gets slower, and makers price that friction in.
Brokers work differently from order books. A broker shows you a single number and fills you itself, which means the two prices still exist inside the quote but are never displayed. That is not deception, and most brokers disclose it in their pricing pages, but it is the reason a platform can advertise low or zero trading fees while remaining perfectly profitable.
Why this matters when you buy bitcoin
The spread is the largest cost most first-time buyers never see, because it is the only one that does not appear as a line item.
Open any broker app and read its buy price and its sell price at the same instant. If it will sell you a coin at 101,000 dollars and buy the same coin back at 99,800, the spread is 1,200 dollars: about 1.19 percent of the midpoint, charged before any labelled fee, and paid again in reverse whenever you sell. On an order book the equivalent test is the top of the book. If the best ask is 100,010 and the best bid is 100,000, crossing costs you 5 dollars per coin from the midpoint.
This is where the split-interface exchanges catch people. Kraken publishes maker and taker rates for Kraken Pro but sells through the simple Buy widget at a spread-inclusive rate. Coinbase runs the same division between simple trades and Advanced Trade. Bitpanda shows no separate commission at all, because its entire margin is the premium inside the quoted price. Luno's instant buys carry a spread while its exchange book charges lower maker and taker fees. In every case, the cheaper door is inside the account you already have.
Spread costs also compound differently from fees. A percentage fee is charged once per trade; a spread is charged on the way in and again on the way out, so a 0.5 percent spread is closer to a 1 percent round trip. If you plan to hold for years, that is tolerable. If you are buying weekly, it is the single line worth optimizing.
Where the spread hides on a zero-fee platform
Zero-fee marketing almost always means spread-funded pricing.
Yellow Card, which serves customers across Africa, posts trading fees that are low or zero and earns on a spread built into its quoted buy and sell prices instead. Coinmama itemizes a commission and a card surcharge, but its quoted price also carries a markup over spot. Changelly names a small swap fee, then prices fixed-rate quotes wider than floating ones, because locking a rate for you is inventory risk it has to charge for.
None of this is hidden in the legal sense. It is disclosed in fee pages that nobody reads, and it is invisible in the moment because the app shows one confident number. The test that cuts through all of it takes ten seconds: note the quoted price, then look up the spot price on an independent source, and treat the difference as your real cost.
Bid-ask spread vs maker and taker fees
A maker or taker fee is a published percentage the exchange adds to your receipt; the spread is a price difference the market imposes before the exchange charges anything. You can pay a 0.10 percent taker fee into a wide book and lose more to the spread than to the fee, or pay 0.40 percent into a tight book and lose almost nothing beyond it. The distinction matters because only one of the two is negotiable by volume tier: fees fall as you trade more, while the spread is whatever the book offers everybody at that second.