WETH (Wrapped Ether) is ETH deposited into a smart contract that issues the same amount of an ERC-20 token. It is always 1:1 with ETH: you can wrap ETH into WETH and unwrap WETH back to ETH at any time, paying only gas. WETH exists because ETH itself is not an ERC-20 token, while DEXs, lending apps and NFT marketplaces are built around the ERC-20 interface.
Key Takeaways
- 1:1 with ETH, redeemable from the WETH contract at any time.
- Why: gives ETH the ERC-20 approve and transferFrom functions.
- Wrapping and unwrapping cost only gas.
- Each chain has its own WETH contract.
ETH vs WETH
| ETH | WETH | |
|---|---|---|
| Type | Native coin | ERC-20 token |
| Pays gas | Yes | No |
| Needs approval to be spent by apps | No | Yes |
| Value | 1 ETH | 1 ETH |
| Ethereum contract | - | 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 |
How Wrapping Works
- Wrap: you send ETH to the WETH contract (its deposit function) and receive the same amount of WETH.
- Use: WETH behaves like any ERC-20 token; apps need a token approval to move it.
- Unwrap: the withdraw function burns WETH and returns ETH.
Many swap apps wrap and unwrap automatically, so you often trade “ETH” while the route uses WETH behind the scenes.
WETH on Layer 2s and Other Chains
Arbitrum, Base and Optimism each have their own WETH contract that wraps ETH on that network. On BNB Chain, Polygon and Avalanche the token called WETH or “ETH” is usually bridged ETH, not wrapped native coin, because ETH is not the gas token there. To move ETH between networks, use a bridge or cross-chain swap; see bridge to Base and what is a layer 2.
Common Mistakes
- No gas: WETH cannot pay fees; keep some ETH for gas.
- Sending WETH to an exchange that credits only ETH: check that the exchange supports WETH on that network.
- Fake WETH: check the contract address; scam tokens copy the name.
WETH is one example of a wrapped asset; the same idea works for Bitcoin, see what is wrapped Bitcoin.
Related: swap ETH to USDC, gas tokens by chain.
