Read a Swap Quote Before You Confirm

Check slippage by comparing the swap’s live output with its minimum received amount and the tolerance that sets that floor. A swap interface gets a quote from one or more liquidity pools, then asks you to approve a transaction against that estimate. The pool state can change before the transaction executes, so the amount delivered may differ from the quote.

For a token swap, a router may send the trade through several pools, using each pool’s reserves and fee to calculate output. A route with more steps can find a better price, but each pool adds another place where the quoted amounts depend on changing reserves. For route details, see Blackhole swap route differences. The quote is like a map drawn from current traffic: useful for choosing a path, but not a promise about conditions when you arrive.

What does slippage tolerance mean?

Slippage tolerance is the largest shortfall from the quoted output that the transaction will accept. For an exact-input swap, the interface uses the quote and your tolerance to set a minimum output. If the transaction would deliver less than that floor, the smart contract reverts the swap instead of completing it.

For example, a quote might show 100 tokens and a minimum received amount slightly below 100. That lower number is the contract’s limit; it is not a second quote or a fee. A wider tolerance lowers the minimum and makes execution more likely when the market moves, but it also lets the trade complete at a worse output. A tighter tolerance protects the output floor, but a small change in pool prices can make the transaction fail. A failed transaction may still consume network fees.

Which numbers should you check in the swap preview?

Read the output, minimum received, route, and slippage setting together. The quote describes the expected result under the pool conditions used by the interface. Minimum received tells you the least output you have agreed to accept. The setting controls how far below the quote that floor can sit.

• Output amount: the interface’s current estimate of what you will receive.
• Minimum received: the contract-enforced floor for the completed swap.
• Route: the pools or token pairs used to reach the destination token.
• Slippage tolerance: the allowed gap between the estimate and the minimum.

Also compare the price impact shown in the preview with slippage. Price impact estimates how the trade itself changes pool prices as it uses available liquidity. Slippage describes the difference between the quoted result and the result the transaction can accept after pool conditions move. A large trade can have material price impact even if the quote stays unchanged while you review it.

When should you change the slippage setting?

Change the setting only when the preview shows a reason the current floor may be too tight or too loose. If the estimated output and minimum are close and the route is clear, a narrow tolerance gives stronger protection against an unexpectedly poor execution. If the transaction repeatedly fails because pool prices move before it executes, a modestly wider limit may allow it through, at the cost of accepting less output.

Before confirming, check that the input token, amount, destination token, route, minimum received, and tolerance match your intent. Treat the minimum as your execution boundary. If that amount is too low, adjust the trade or wait for a better quote instead of signing on the assumption that the displayed estimate is guaranteed.