How to Check a Token Swap’s Minimum Output

If you are about to swap tokens, check the minimum output before you approve the trade. It shows the least you agree to receive if the price changes before the trade completes. A swap quote is an estimate; the minimum sets a boundary.

For example, a quote might show 0.005 WBTC for 500 USDC. WBTC is a token designed to track Bitcoin’s value. If you set a 1% tolerance, your minimum is 0.00495 WBTC. For a deeper explanation of which Fermi swap route fits a trade, read the route guide; here, the focus is checking that minimum before you proceed.

What does the minimum output protect?

The minimum output limits how much less you will accept than the quote. A swap uses available token reserves, the amounts held for trading, to calculate its price. If those reserves or the market price change before your trade is processed, the actual output can differ.

The quoted output already reflects the estimated effect of your trade on the price. This is called price impact. Slippage tolerance is the extra movement you allow between the quote and execution. Keeping the two separate helps: a poor quote may be unattractive even when its slippage tolerance is low.

How do you check it before swapping?

1. Confirm both tokens. Check that the token you are spending and the one you want to receive are correct. For unfamiliar tokens, verify the token’s contract address, a unique identifier on its network, from a source you trust.
2. Enter the amount you plan to trade. Review the estimated output. A larger trade can have greater price impact when available reserves are limited.
3. Find the minimum output and tolerance. The minimum should be no lower than the least amount you are willing to accept. If the tolerance is shown as a percentage, calculate: quoted output × (1 − tolerance). For 0.005 WBTC and 1%, that is 0.00495 WBTC.
4. Compare the minimum with your goal. If you need at least 0.00498 WBTC, a 0.00495 minimum does not meet your goal. Reduce the trade amount or wait for a better quote, then check again.
5. Review the network cost, then approve. Gas is the network fee for processing a transaction. A trade that misses its minimum may fail, and the network can still charge gas for that failed attempt.

When should you stop and check again?

Stop if the minimum is below your acceptable amount or the quote changes while you review it. A very loose tolerance can let a trade complete at a much worse price. A very tight one can cause a failure if the price moves slightly.

Before using Fermi swap or another wallet-based token exchange, decide the least output you will accept. Then compare that amount with the displayed minimum for this specific trade. Proceed only when the numbers still suit your plan.