A screen quotes 100.00; the completed order reports an average fill of 100.60. That 0.60 difference is slippage, and it can be favourable or unfavourable.
The venue, order type, available depth, order size, latency and market movement all shape the result. Centralised order books and decentralised pools create it through different mechanics, so neither venue type is automatically better.
Slippage, spread and price impact are different
The bid–ask spread is the gap between the best available buying and selling prices. Price impact is the change an order causes as it consumes available liquidity. Slippage compares the quoted or expected price with the final execution price; it can reflect market movement, price impact or both. Trading fees are separate again.
Suppose an order to buy 10 units is expected to execute at $100, but fills across several prices for an average of $100.60. Slippage is $0.60 per unit, or 0.6% relative to the expected price. The calculation should use the volume-weighted average fill, not only the price of the last fill.
A lower displayed fee does not necessarily mean a lower total cost. Spread, slippage and explicit fees must be assessed together.
Why slippage happens on order-book exchanges
A market order seeks immediate execution against the best orders currently available. It controls urgency, not the final price. The US investor education service explains the same core distinction between market and limit orders: a market order generally prioritises execution, while a limit order controls the worst acceptable price but may not fill.
On a crypto order book, a large market order may consume several price levels. A quote can also change between submission and matching. Slippage therefore tends to increase when:
- the order is large relative to visible and hidden liquidity;
- the spread is wide or the book is shallow;
- volatility rises around news, liquidations or market openings;
- the venue is slow, congested or fragmented;
- the asset trades in an illiquid pair.
A centralised venue can have deep liquidity in one pair and poor liquidity in another. The label “CEX” or “DEX” alone does not predict execution quality.
How slippage works in an automated market maker
On an automated market maker, a swap changes the pool’s asset balance and therefore its quoted price. The larger the trade is relative to usable liquidity, the greater the price impact is likely to be. Concentrated liquidity can make this relationship depend on the active price range rather than the pool’s headline value.
Uniswap’s current swap documentation describes swaps as trades against liquidity pools. A wallet normally asks the user for a slippage tolerance: the maximum adverse movement accepted before the transaction reverts. This is a protection limit, not an estimate of the final cost.
Setting tolerance too low can cause repeated failures and wasted network fees. Setting it unnecessarily high can authorise a much worse fill and may increase exposure to transaction ordering or sandwich attacks. Ethereum’s explanation of maximal extractable value shows why public transaction ordering matters for onchain execution.
Practical controls
- Check depth, not only the last price. Review the order book or the DEX quote for the intended size. A small test quote does not describe a large order.
- Use a limit order when price control matters. Accept that it may remain open, fill partially or never execute.
- Split with care. Smaller orders may reduce immediate impact, but repeated fees, price movement and information leakage can offset the benefit.
- Compare liquid routes. Evaluate the exact pair, venue, pool and network. A routed DEX quote can use several pools, each with different costs and risks.
- Set a deliberate tolerance. Use the smallest tolerance compatible with current liquidity and volatility rather than accepting a wallet default mechanically.
- Include every cost. Add exchange fees, network fees, spread and any bridge or withdrawal cost to the realised execution price.
Traders using leverage should be especially conservative because a poor fill changes entry price and liquidation distance. The margin and liquidation guide traces that additional risk. For DEX trades, the broader DeFi guide covers smart-contract, oracle and liquidity dependencies.
What slippage settings cannot do
No setting guarantees a profitable price, available liquidity or successful settlement. A limit protects one dimension of execution; it does not verify the token, contract, venue or counterparty. Likewise, positive slippage is not free profit: total performance still includes the spread, fees, tax treatment and later price movement.
Before submitting the order, write down the maximum acceptable average price and total cost. That gives the limit, quote and completed fill a concrete baseline for comparison.
Editorial note: this guide was fully reviewed and rewritten on September 3, 2026. It provides general educational information, not trading or financial advice.
