Market order
A market order is an instruction to buy or sell right away at the best price available in the order book. It fills instantly, but the exact price is not guaranteed.
How it works
A market order does not wait for a price. It takes the best opposite orders from the order book (the list of buy and sell orders). A buy takes the cheapest sell offers, a sell hits the highest bids. If the first level is too small for your size, the order eats into the next levels and your average price gets worse.
The gap between the price you expected and the price you got is called slippage. It is tiny on liquid pairs like BTC/USDT in a calm market and large on small coins, at night or during news. Many platforms also charge market orders the taker fee, which is usually higher than the fee for limit orders.
Use a market order when speed matters more than price: getting out of a losing trade fast, closing before a big news release, or catching a breakout that may run without you. Stop-losses often trigger a market order too.
The order book shows 0.5 BTC for sale at 60,000 and another 0.5 BTC at 60,050. You market-buy 1 BTC. Half fills at 60,000, half at 60,050, so your average is 60,025. That is 25 dollars of slippage per coin.
On a small coin there is only 200 dollars offered at 1.00, then orders at 1.05 and 1.10. A 1,000 dollar market buy eats several levels and the average fill can land around 1.06, about 6% above the price you saw on screen.
The classic mistake is a large market order on a thin market (few orders in the book) or right when news hits. You can fill far from the price on the chart. Look at the order book and the spread before you trade. If you are not in a hurry, use a limit order, and split a large size into smaller pieces.
Questions and answers
What is a market order in simple terms?
It is a command to buy or sell right now at whatever price is available. The trade goes through immediately, but you do not know the exact price in advance.
What is the difference between a market order and a limit order?
A market order fills at once at the current price. A limit order fills only at your price or better, but it may never fill.
Why did my market order fill at a different price?
Because of slippage: price moved while the order was being sent, or the best level did not have enough size and the rest filled at worse prices.
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Updated: 2026-10-19