Cross-chain · Base → Polygon

Swap WETH from Base to USDC on Polygon

Swap WETH from Base to USDC on Polygon. Base WETH leaves, and Circle's native USDC arrives on Polygon chain 137.

Approve 0x4200000000000000000000000000000000000006 on Base, chain 8453, and confirm that token on Basescan. Native ETH, 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE, is not the input. Receive 0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359 on Polygon, chain 137. That is Circle's native USDC, 6 decimals, on Polygonscan. It is not USDC.e at 0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174. It is not Tether. You still need POL to move it, because USDC is not the gas coin.

Diagram for Swap WETH from Base to USDC on Polygon — WETH leaves Base. USDC is what can arrive on Polygon.

The allowance is only the Base wrapper

The router needs permission to take WETH. Read the spender and the cap. The signature costs ETH on chain 8453. It does not approve USDC on Polygon, and it does not move native ETH. If the wallet shows an ETH balance and an empty WETH balance, wrap first or change routes. Declining the allowance stops the trade cleanly.

Native USDC versus USDC.e

Circle's current Polygon USDC is 0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359. The older bridged token is 0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174. Both have been displayed as USDC. A lending market still wired to the bridged address will not accept this credit. Six decimals match either token, so decimals alone will not save you. Open Polygonscan.

Wrong input, wrong output

Wrong if you meant to sell native ETH rather than WETH. Wrong if the destination dollar is Tether at 0xc2132D05D31c914a87C6611C10748AEb04B58e8F. Wrong if you wanted POL so you could pay fees. Wrong if you wanted WETH to remain WETH on Polygon. Wrong if the USDC only needed to stay on Base.

Fee coin after a dollar credit

Trade on Polygon is the reminder that POL pays chain 137. WETH you sold was on Base. USDC you bought cannot substitute. Basescan shows the wrapper debit. Polygonscan shows the USDC credit. No duration is promised for the gap between those pages. If the minimum USDC is poor, leave it unsigned.

Legal

Risk disclosure

XAUConnect is a non-custodial swap aggregator. Digital assets are volatile and may lose value rapidly. Content on this page is educational and not investment advice. Verify every contract address on the official block explorer before approving a transaction.

Frequently asked questions

What is the best way to swap WETH from Base to USDC on Polygon?

Approve 0x4200000000000000000000000000000000000006 on Base, chain 8453, and confirm that token on Basescan. Native ETH, 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE, is not the input.

Which USDC contract should Polygonscan show?

Circle's native USDC at 0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359. USDC.e at 0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174 is the bridged token and is not this route. Tether is 0xc2132D05D31c914a87C6611C10748AEb04B58e8F. Match the address in the app to the address on the quote before you sign. USDC.e and native USDC are not interchangeable on Polygon chain 137.

Do I approve WETH on Base?

Yes. The input is 0x4200000000000000000000000000000000000006, an ERC-20 on chain 8453. The router needs an allowance. Native ETH is the gas coin that pays for that approval, and it is not the asset being sold. Review the spender. The allowance does not extend to Polygon. A later spend of USDC on chain 137 is a new signature, paid in POL.

Can this USDC pay Polygon gas?

No. Gas is POL, the native coin on chain 137, often written as 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE. USDC is an ERC-20 from Circle with 6 decimals. ETH on Base does not pay Polygon fees. Without POL, the USDC can show on Polygonscan and still be stuck. Fund the gas coin before you try to move it.

Live execution

Trade on XAUConnect

Open the swap page with this cross-chain route pre-selected, then connect your wallet on the source chain to quote and execute. You keep the keys.

Swap cross-chain Explore markets

Continue exploring

Related markets, guides & networks

Next pages on this subject. Read them before you trade.

Networks

Tokens

Guides

Articles

Build programmatically

Swap via API for bots and AI agents: quotes, builds, and cross-chain routes.

Developer quickstart