For a straightforward swap, use the asset type the trade expects and keep native ETH aside for network costs. On Ethereum, ETH and WETH can track the same value, but they work differently inside apps.
What changes when ETH is wrapped?
Wrapped ether (WETH) is ETH held by a smart contract, which is a program on the blockchain, with an ERC-20 token issued in its place. ERC-20 is a shared set of rules that lets apps handle tokens in a consistent way.
- ETH is Ethereum’s native currency.
- WETH is an ERC-20 token backed one-for-one by ETH held in a contract.
- ETH pays Ethereum network fees, even when the swap uses WETH.
Think of ETH as cash and WETH as a prepaid card loaded with the same amount. The value may match, but a shop that accepts cards can process the card more easily than cash.
Wrapping 0.1 ETH gives you 0.1 WETH; unwrapping burns that WETH and returns the ETH. The amount is one-for-one, but wrapping and unwrapping are separate blockchain actions, so each uses gas—the network’s fee for processing actions.
Why can a swap ask for WETH?
A swap app may handle WETH and other ERC-20 tokens through the same token rules. Native ETH works differently, so the app or trade route may need to convert it to WETH before using that path.
A decentralized swap uses blockchain transactions to exchange tokens from your wallet. When comparing a route that uses ETH with one that uses WETH, check the final asset you’ll receive and the network cost for the full route, including any conversion.
If you’re weighing that kind of trade, Fermi swap is a way to exchange tokens directly from your wallet. The important check is whether the trade is using ETH or WETH at each step, since they are separate balances.
Fermi is a decentralized swap service for exchanging tokens from your wallet. A trade involving WETH still needs native ETH in the wallet to pay Ethereum network fees.
What happens during a token swap?
For an ERC-20 token, a swap often starts with an approval. This is a wallet-authorized allowance, or spending limit, that lets a contract move the approved token amount for the trade.
The EIP-20 token standard describes this approval-and-transfer pattern. Once the token can be moved, the swap route takes the input asset and returns the output asset; if ETH needs wrapping, that conversion is part of the route or a separate action.
For example, swapping 0.1 WETH for another token uses WETH as the input, while the Ethereum transaction fee is paid in ETH. If the wallet holds 0.1 WETH but no ETH, it may have enough value for the swap and still be unable to submit the transaction.
What should you check before swapping?
Check the asset name and token balance shown in your wallet, then confirm whether the trade expects ETH or WETH. Keep enough ETH for the transaction, and read any approval request so its token and spending limit make sense for the swap.
Wrapped versions of other assets follow the same broad idea, but their backing and redemption depend on the token’s issuer or bridge. WBTC, for example, represents bitcoin as an Ethereum token; its one-for-one relationship depends on the arrangements behind that token, not on Ethereum itself.
Ethereum.org explains WETH’s one-for-one deposit and redemption, while EIP-20 sets out the common token rules used by many apps. In practice, I’d check the exact token, the route’s final asset, and the ETH left for gas before confirming.
ETH is Ethereum’s native currency and pays network fees; WETH is its token-form representation for apps that use ERC-20 rules. Know which one the swap uses, and keep ETH available for the transaction.
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