What is the bid-ask spread?
Nobody sends you an invoice for the spread. It is simply the price you pay for wanting to trade now rather than at the price you would prefer — and for an active trader it is often larger than the fees the exchange actually charges.
Who earns the spread?
Market makers — firms and bots that keep both a bid and an ask resting in the order book at all times. They buy at the bid, sell at the ask, and keep the difference in exchange for providing the liquidity everyone else trades against. When you use a market order you are their customer; when you rest a limit order you are, for that moment, doing their job and can collect a maker rebate instead of paying a taker fee.
How much does the spread really cost?
Cost per round trip ≈ the full spread as a percentage of the position, if both legs are market orders. The table assumes a $2,000 position and 20 round trips a day, which is an ordinary day for a scalper.
| Pair | Spread | Cost per round trip | 20 trips a day | Over 250 trading days |
|---|---|---|---|---|
| BTC/USDT ($77,500.0 / $77,500.5) | 0.0006% | $0.01 | $0.26 | $65 |
| Large-cap altcoin | 0.05% | $1.00 | $20 | $5,000 |
| Thin altcoin ($1.000 / $1.004) | 0.40% | $8.00 | $160 | $40,000 |
Percentages are stated assumptions, not live quotes; substitute the spread you see on your own pair. Exchange fees come on top.
The last column is the point. A $2,000 account scalping a thin pair would need to earn 2,000% a year just to pay its own spread. Nobody scalps thin pairs profitably for long; the spread makes sure of it.
When does the spread widen?
Whenever makers get nervous: around news, in the minutes after a large liquidation, during low-liquidity hours, and in any crash. Their quotes pull back or disappear, the gap opens, and the market order you send to escape pays multiples of the normal spread. This is why a stop placed in advance, at a known level, beats a panic exit: the panic exit is submitted at the moment the spread is widest.
How do I avoid paying it?
Three levers, in order of size: trade liquid pairs (BTC, ETH and a handful of majors have spreads a hundred times tighter than the long tail); use limit orders when timing is not critical, so you earn the spread instead of paying it; and trade less — every round trip you skip is a spread you keep. Add the spread to your expectancy maths: a method that makes +0.1R per trade on a pair with a 0.4% spread may be negative once the spread is counted.
FAQ
Is the spread the same as slippage? No. The spread is the resting gap between best bid and best ask; slippage is the extra you pay when your order is larger than the size resting at those prices and walks further into the book. Both are costs of immediacy.
What is a normal spread? On BTC/USDT at a major exchange, well under 0.01%; on liquid altcoins, 0.02–0.1%; on thin pairs, 0.3% or more. Measure it on your own venue at the time of day you trade.
Do limit orders avoid the spread completely? If they rest and fill, yes — you are paid the spread rather than charged it. The cost is that a resting order may never fill, so you can miss the move you were waiting for.
Pick the venue where the spread is smallest for what you trade
Spread depends on the venue and the pair. The matcher weighs liquidity by your size and what you plan to trade.
Every key term, one roadmap
The whole slide course — ten free PDF parts, 328 pages.
The spread is the first of three costs of immediacy; slippage is the second and the taker fee the third. Lesson 8 — liquidity and spread shows how to measure depth before sizing a position, and Lesson 6 explains when a limit order is worth the risk of not filling.