Why does my MON get wrapped to WMON during the swap?

UniswapV2 pools require ERC-20 tokens on both sides. Native MON is not ERC-20, so the router wraps it to WMON inside the same transaction. You sign once and pay one round of gas; the wrap is invisible to you.

Do I need to approve before swapping MON?

No. Native MON does not have an ERC-20 allowance. The approval step only applies when the input token is an ERC-20 like USDC, USDT, or WMON.

How is the MON/USDC rate calculated?

PuddleSwap reads live reserves from the WMON/USDC pool and applies the constant-product formula. The output USDC amount you see is the net amount after the 0.30% LP fee.

What's the minimum MON I can swap?

There is no protocol minimum. Practical minimums depend on gas: very small swaps cost more in gas than the trade itself is worth on testnet, so most users swap at least a few MON.

How to Swap MON for USDC on Monad Testnet

4 min read · Updated 2026-04-27

Convert MON to USDC when you want a USD-pegged balance instead of holding the volatile native token. Useful for testing stablecoin flows, parking value through volatility, or paying for things priced in dollars.

The route

Path: MON → WMON → USDC.

The router accepts native MON directly. It first wraps your MON to WMON via the WMON contract's deposit() call, then trades the WMON into USDC through the WMON/USDC pool. Everything happens in a single transaction.

Step by step

Open PuddleSwap and connect your wallet to Monad Testnet (chain ID 10143).
Pick MON as the input token and USDC as the output token.
Type the MON amount you want to swap. The output USDC amount updates automatically based on the best route.
Check the slippage tolerance. The default is 1%; raise to 2-3% for thin pools, lower for deep pools.
Click Swap and sign the transaction in your wallet. There is no approval step because MON is the native gas token, not an ERC-20.
After one block, USDC appears in your wallet as an ERC-20 balance.

Slippage and fees

USDC is a USD-pegged stablecoin, but the underlying pair is WMON/USDC, which is volatile (MON's price moves against USD). Price impact scales with how much of the pool's reserves your swap consumes; large swaps may need higher slippage tolerance.

All UniswapV2-style pools on PuddleSwap charge a 0.30% LP fee on the input side. PuddleSwap itself does not charge an app-level fee. Gas is paid in test MON.

About MON

Monad's native gas token. Required for paying gas on Monad Testnet. Free from the official faucet. See the MON token page for the full address, decimals, and live pools.

About USDC

USD-pegged stablecoin issued for Monad Testnet. Stable rate, deep core-pair pools, claimable from the stable faucet. See the USDC token page for the full address, decimals, and live pools.

Open PuddleSwap to swap MON for USDC now, or read about star routing for the full routing model.

FAQ

Why does my MON get wrapped to WMON during the swap?: UniswapV2 pools require ERC-20 tokens on both sides. Native MON is not ERC-20, so the router wraps it to WMON inside the same transaction. You sign once and pay one round of gas; the wrap is invisible to you.
Do I need to approve before swapping MON?: No. Native MON does not have an ERC-20 allowance. The approval step only applies when the input token is an ERC-20 like USDC, USDT, or WMON.
How is the MON/USDC rate calculated?: PuddleSwap reads live reserves from the WMON/USDC pool and applies the constant-product formula. The output USDC amount you see is the net amount after the 0.30% LP fee.
What's the minimum MON I can swap?: There is no protocol minimum. Practical minimums depend on gas: very small swaps cost more in gas than the trade itself is worth on testnet, so most users swap at least a few MON.