DEX swap costs: separating pool fees, gas and interface charges

Reconcile the quote with the receipt

Suppose an interface quotes 997 units received from a 1,000-unit reference value after pool costs and price impact. If network execution separately costs a hypothetical 2 units in the same valuation currency, the net outcome is 995. Subtracting the embedded 3 again would double-count it.

Use a common valuation time when converting native gas into dollars. A wallet’s maximum gas budget is not necessarily the amount paid.

Separate the charge from its recipient

The trader’s total pool fee and the portion ultimately credited to LPs are different numbers. The retrieved Uniswap documentation describes protocol shares and version-specific rules. An LP revenue figure cannot be substituted for the fee a trader paid.

Aave’s swap-feature documentation gives an example of interface fees that vary by operation and pair. Check the applicable quote and policy; this article does not assume a permanent fee schedule.

A failed trade can still have a cost

If an on-chain transaction is included but reverts, gas used in execution can still be charged even though the swap does not settle. A quote that never becomes an included transaction is a different event. Signed-order systems can arrange for a filler to pay execution gas, but someone still bears that cost economically.