Why blockchains charge fees
A blockchain fee pays for the computation or block space needed to include a transaction. On some networks it is called gas. It is normally paid in the network's native asset, such as ETH on Ethereum, even when the token being moved is USDC or another asset.
Fees are not a fixed postage stamp. They can change with network demand, transaction complexity, and the chain you use. A transfer that is cheap on one network may cost more on another, so the token name alone is not enough to compare routes.
The costs that can appear in a swap
An on-chain swap can include network gas and a liquidity-pool or protocol fee. An instant exchange route may include the provider's exchange rate and the cost of a payout transaction. Card purchases can also include payment-provider and card-network costs. The exact mix depends on the route.
A transparent quote makes the important outcome visible: how much you send and how much you receive. This matters more than trying to add several moving costs manually, because a rate can already reflect costs that are not shown as separate line items.
How to compare fees properly
Request quotes for the same input amount, asset, and network, then compare the final output and the stated conditions. Check whether the quote is floating or fixed, whether a minimum applies, and whether it requires network gas from your own wallet.
Do not assume the lowest visible network fee creates the best result. A route with low gas can still have limited liquidity or a less favorable conversion. Likewise, the fastest route is not always the least expensive. The final quoted output is the useful comparison point — which is why Tadswap shows the quote that lost beside the one that won.
Avoiding fee surprises
Keep a small amount of a network's native asset in a self-custody wallet before attempting a DEX transaction. Without it, the wallet cannot pay gas even if you hold the token you want to swap.
Review the quote shortly before you act and avoid trying to send an exact maximum balance. The network needs room for fees, and a quote can expire or change. This is educational information, not financial advice.