Slippage: the cost nobody quotes you

You saw one price and received another. The gap is real money and it grows exactly when you can least afford it.

Slippage is the difference between the price you expected and the price your order actually filled at. It is not a fee, nobody quotes it, and it can easily exceed every fee you pay.

Why it happens

A market order does not buy at "the price". It buys whatever is offered, starting at the best price and working outward until the order is filled. If the order book is deep, that walk is tiny. If it is thin, your own order pushes price against you.

When it gets worse

• Thin markets. Smaller coins, obscure pairs, minor exchanges.
• Large orders. Slippage scales with your size relative to the book.
• Volatile moments. News, liquidation cascades, the open of a major session.
• Stop-market triggers. These fire precisely when the market is moving fast, which is exactly when slippage is worst.

How to reduce it

1. Use limit orders to enter. You give up certainty of execution and gain certainty of price. For entries, that is usually the right trade.
2. Check book depth first. The order book panel shows resting bids and asks; if your intended size is a meaningful fraction of it, split the order.
3. Trade the deeper venue. The exchange volume panel shows where real liquidity sits.
4. Avoid the first seconds of a violent move. Spreads widen exactly then.
5. Keep stop-market for exits. Here, certainty of execution matters more than price.

Measuring what it actually costs you

Slippage is invisible in a fee schedule, which is why most traders never quantify it. It is straightforward to measure: compare the price you saw when you clicked with the average price you received. That difference, as a percentage, is your slippage on that trade.

Do it for ten trades and you will have a personal figure — and for most active retail traders on smaller pairs, that figure exceeds the trading fee they worry about. On a $5,000 position, 0.2% slippage is $10 per side, or $20 per round trip, against perhaps $5 in fees.

The exit test panel does this calculation in advance rather than after the fact, by walking the live order book with your intended size.

The moments slippage is worst

The last row deserves attention. Stop orders trigger during fast moves by definition, which means the trade you most need filled is the one most likely to fill badly. This is not an argument against stops — it is an argument for placing them where they will not be hit by noise, and for sizing positions so a poor fill is survivable.

Slippage on decentralised exchanges is a different problem

On a DEX the mechanism changes entirely. Price comes from a pool formula rather than a book, so your trade size relative to pool depth determines the cost directly — and there is a second, worse issue.

Reducing it in practice

1. Enter with limit orders. Slippage on entry becomes zero by definition.
2. Check depth against your size first, every time.
3. Split large orders into pieces spread over minutes rather than one order that eats the book.
4. Trade during liquid hours. The best hours panel shows when depth actually exists for your market.
5. Prefer deeper venues even at a slightly higher fee — depth beats fee schedule at any meaningful size.
6. Keep stop-market for exits, and accept the cost as insurance rather than trying to optimise it away with a stop-limit that may not fill.

Common questions

Is slippage the same as the spread?

Related but not identical. The spread is the gap between best bid and best ask, paid on any market order. Slippage is the additional cost of walking further into the book because your order was larger than the best level could fill.

Does slippage affect limit orders?

Not on price — a limit order fills at your price or better, never worse. The cost of a limit order is different: it may not fill at all, and a missed entry can be more expensive than any slippage would have been.

How much slippage is acceptable?

It depends entirely on your holding period. For a scalp targeting half a percent, 0.2% slippage destroys the trade. For a position held weeks, the same 0.2% is irrelevant. Judge it against your expected move, not against an absolute number.