Slippage is the difference between the price or output a trader expects when placing an order and what the trade actually receives when it executes. A quote is based on market conditions at a particular moment; those conditions can change before the order is filled. Slippage can be favorable or unfavorable, and it can occur on centralized exchanges as well as decentralized exchanges (DEXs).
Slippage and price impact
Price impact is the change in a market price caused by the size of a trade against the available liquidity. On an automated market maker (AMM), a swap changes the pool’s token balances, so a large order relative to the available liquidity can receive a worse average price than the pool’s starting price. In an order-book market, a large market order can consume several price levels.
Slippage describes the gap between an estimate and the eventual execution. A DEX quote may already include the price impact expected from the trade at the time of the quote. The execution can then differ further if the pool or order book changes before the transaction completes. Some interfaces use “slippage” loosely for the whole difference from a reference price, so check how a particular app defines the displayed figure.
Slippage is not itself a trading fee. Protocol fees, pool fees, network fees, and any interface fee are separate costs, although an app may combine some costs when it shows a net amount.
What slippage tolerance means
Many on-chain swap interfaces let a user set a slippage tolerance. For a typical exact-input swap, the transaction encodes a minimum acceptable output based on the quote and the chosen tolerance. If the actual output falls below that minimum before execution, the swap normally reverts rather than completing at the worse rate. A reverted transaction can still consume network fees.
A tighter limit rejects more price movement, which can cause a transaction to fail during volatility or when a route has little liquidity. A wider limit allows a larger difference from the quote and can expose the user to a worse fill. The setting is not a prediction of the price and does not guarantee that a trade will execute. Interfaces and protocols implement these controls differently; limit orders and intent-based swaps may use different protections.
Why the quote can change
- Trade size and liquidity: A large trade relative to the available pool or order-book depth can move the execution price.
- Market movement: Other trades can change the price while an order is waiting to be included or matched.
- Transaction ordering: On public blockchains, the order in which transactions are included can affect the state a swap encounters.
- Routing and pool design: A route through several pools, concentrated liquidity, token behavior, and the venue’s execution rules can all affect the final output.
Slippage and MEV
Maximal extractable value (MEV) refers to value gained by influencing transaction ordering or inclusion. A sandwich attack is one example: a searcher places a trade before and another after a visible swap, moving the pool price against that swap. A generous minimum-output limit may leave more room for an unfavorable execution, but tolerance alone does not prove that a sandwich occurred or prevent every form of MEV. Private transaction routes and other protections have their own trade-offs and are not universal guarantees.
How to read a swap quote
Before signing, compare the quoted output with the minimum output, inspect any price-impact warning, and check which fees are included in the displayed total. If the minimum output is much lower than the quote, pause and review the route, asset contract, pool depth, and current market conditions. A failed swap may be preferable to accepting an execution price you did not intend. No single tolerance percentage is right for every asset, venue, or transaction.
Related Terms
- AMM — an exchange design that prices trades using liquidity pools and rules encoded in software.
- Liquidity Pool — assets supplied to a trading venue that help determine how much a trade can execute.
- MEV — value extracted by changing which transactions are included or their order.
See Also
- What Is MEV — And Why Every Ethereum Transaction Is a Game — explains transaction ordering and how it can affect swaps.
- Does Ethereum TPS Include Layer 2 Transactions? — gives context for transaction processing and the different networks a swap may use.
- Why Does Bitcoin Still Move With the Stock Market? — explores broader market moves that can make a quote stale before execution.
Looking for a crypto swap service? Compare supported assets and networks on ChangeNOW.
Social Media Sentiment
Two Reddit discussions from May 2026 show recurring user questions rather than a representative market survey. In one r/ethereum thread, a trader asked why the received amount differed from a swap quote despite setting a tolerance; commenters discussed liquidity depth and possible transaction-ordering effects, but the thread did not establish the cause. In a separate r/defi discussion, users asked what a tolerance setting allows and why trades can fail. Together they illustrate confusion about quotes, minimum output, and execution risk, not the frequency of any particular cause.
Last updated: 2026-10
Sources
- Uniswap Labs, “What is price impact?” — defines trade-driven price impact and explains why pool liquidity and order size affect it.
- Uniswap Labs, “How to change slippage on the Uniswap Web app” — describes slippage as the difference between expected and received output and explains the tolerance control.
- ethereum.org, “Maximal extractable value (MEV)” — explains transaction-ordering strategies, including sandwich trading on decentralized exchanges.
- Adams, Chan, Markovich, and Wan, “Don’t Let MEV Slip: The Costs of Swapping on the Uniswap Protocol” — studies the difference between quoted and realized execution prices and separates benign from adversarial slippage.