Ordering
Market or limit order — which first?
Rather than giving you a rule to memorise, this explains what the exchange is actually doing when you press buy. Once that is clear, which button to press stops being a question.
A market order buys certainty of filling, and pays whatever the market gives you.
A limit order buys certainty of price, and accepts that it might not fill at all.
You are always trading one of those two certainties for the other. There is no option that gives you both.
What the order book is#
An exchange does not sell you bitcoin. It matches you with other people who want to trade.
At any moment there is a list of standing offers — people willing to sell at various prices, and people willing to buy at various prices. That list is the order book. It might look roughly like this:
| Side | Price | Quantity available |
|---|---|---|
| Sellers | 50,020 | 2.0 |
| Sellers | 50,010 | 0.8 |
| Sellers | 50,005 | 0.3 |
| — the gap between these two is the spread — | ||
| Buyers | 50,000 | 0.5 |
| Buyers | 49,995 | 1.2 |
| Buyers | 49,980 | 3.0 |
The “current price” you see quoted is simply the price of the most recent completed trade. It is history, not a promise about your order.
What a market order does#
A market order says: fill me now, at whatever prices are available.
It walks up the sell side of the book taking the cheapest offer first, then the next, until your order is filled. Using the book above, a market buy for 0.3 fills entirely at 50,005. A market buy for 1.5 takes all 0.3 at 50,005, then all 0.8 at 50,010, then 0.4 at 50,020 — and your average price is somewhere above where you started.
It always fills. The price is whatever it turns out to be.
What a limit order does#
A limit order says: buy for me, but not above this price.
Two things can happen. If somebody is already offering at or below your limit, it fills immediately — exactly like a market order but with a ceiling. If nobody is, your order joins the book as a standing offer and waits until somebody sells into it, or until you cancel.
The price is capped. Whether it fills is not guaranteed.
This is the most common misunderstanding. If you set your limit slightly above the current asking price, it fills instantly — you simply also got a guarantee that you would not pay more than that.
That combination is usually the most practical choice: near-certain immediate fill, plus a hard ceiling. More on this in so which one.
Where slippage comes from#
Slippage is the gap between the price you saw and the price you got. It has two causes, and both are visible in the book above.
-
Your order was bigger than the best offer
You consumed the cheapest offer and had to keep going up the book. The larger your order relative to what is available, the more this matters.
-
The book moved between looking and pressing
The market runs continuously. Between the quote rendering on your screen and your order arriving, other people traded.
For a small first purchase on a major pair like BTC, slippage is typically negligible — the book is deep and your order is small relative to it. It matters when the amount is large, or the asset is thinly traded.
Maker and taker fees#
This is why the two order types can also differ in cost.
- An order that fills immediately against what is already on the book takes liquidity. You are a taker.
- An order that sits on the book waiting makes liquidity. You are a maker.
Exchanges usually charge takers more, because makers are providing something the exchange wants. A market order is always a taker order. A limit order is a maker order only if it does not fill immediately.
The difference is small — typically a fraction of a percent — and it is not worth optimising for on a first purchase. It is worth knowing so the two slightly different fee numbers do not confuse you. See the fees article.
So which one#
| Your situation | Use | What you give up |
|---|---|---|
| First purchase, small amount, want it done | One-click buy, or a market order | 1–2% on one-click. Fewest places to go wrong, which is worth something the first time |
| Done it before, just want to buy now | Limit order set slightly above the current ask | Almost nothing. Near-certain instant fill plus a price ceiling — the most practical combination |
| You have a specific price in mind and can wait | Limit order at your target | It may never fill. You might watch it move away from you |
| Larger amount | Several smaller limit orders | More effort, and more time watching. Reduces the cost of eating through the book in one go |
All of the above assumes you are on the spot screen. If you can see leverage multipliers, long/short buttons, margin or a liquidation price, none of this applies because you are not buying anything. See the first common mistake.
Common questions#
Can I cancel a limit order?
Yes, at any time before it fills, and cancelling is free. The money is held against the open order while it waits, and is released when you cancel. A filled order cannot be cancelled — see can I undo a purchase.
My limit order only partly filled.
Normal. Somebody sold into part of it and the rest is still waiting. You can leave it, or cancel the remainder.
What is a stop or stop-limit order?
An order that only becomes active once the price reaches a trigger. Useful for exits and generally unnecessary for a first purchase — it adds a way to get the setup wrong without adding anything you need.
Is one-click buy just a market order?
Functionally similar from your side, but priced differently: it quotes a single all-in price with a markup built in, rather than routing you to the order book. Simpler, and typically 1–2% more expensive.
Should I try to time the price?
This site does not answer that, and you should be wary of anyone who does. Choosing an order type is an operational decision about certainty of fill versus certainty of price — it is not a prediction.
Last updated: 25 August 2026. The order book figures above are illustrative, chosen to show how matching works — they are not quotes. Not investment advice.
Related
- What do the fees actually come to? Including maker and taker
- Can I undo a purchase? What is reversible and what is not
- The full walkthrough: ordering The three numbers to check first