Spread and slippage explained: why your crypto order fills at a different price
You see a price on the screen, tap buy, and the trade executes at something noticeably different. It feels like a glitch, but it is usually the result of two ordinary market mechanics: the spread and slippage. Both exist on every exchange, including Binance, OKX, Bybit and Bitget, and both matter more for less liquid coins and during fast-moving markets. Understanding them helps Australian traders choose better order types, size trades sensibly and avoid unpleasant surprises.
The spread: the gap between buyers and sellers
At any moment, the order book shows the highest price buyers are willing to pay and the lowest price sellers will accept. The difference between them is the spread. If you buy immediately, you pay the seller price; if you sell immediately, you receive the buyer price. Popular trading pairs usually have narrow spreads, while smaller coins can have wide ones.
Instant buy or convert screens may build a spread into the quoted price. Compare the quote with the live order book before accepting it.
Slippage: when your order eats through the book
A market order fills against whatever orders are available. If your order is larger than the volume at the best price, it continues to the next levels, each a little worse. The average price you receive can therefore differ from the price you saw. In fast markets, the book can also change between the moment you tap and the moment the order arrives.
Some platforms let you set a slippage tolerance on certain features. Check the official help centre for how this works where you trade.
Practical ways to limit both
Use limit orders when you are not in a hurry, so that you control the worst acceptable price. Look at order book depth before placing a larger trade, and consider splitting it into smaller parts. Avoid trading thinly traded pairs during major news events, when spreads tend to widen sharply. After each trade, compare the average fill price in your history with the price you expected and note the difference.
Know when to step back
If the spread on a pair looks unusually wide or the book looks thin, it is often better to wait or reconsider. No trade is so urgent that it is worth accepting a price far from fair value without understanding why.
Risk boundary: Australia Crypto Guide
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Scenario checkpoint
- Check the gap between best bid and best ask before trading
- Compare instant-buy quotes with the live order book
- Use limit orders when timing is not critical
- Review order book depth before placing larger trades
- Record the difference between expected and actual fill prices