Price a 350,000 gas sell on Monad before you sign it

Monad uses the gas model a Solidity developer already knows. Each opcode has a weight. The transaction has a limit. The sender pays a fee derived from the base fee and a priority tip, in MON. The part people misread is which number to multiply. Multiply the gas the receipt used. The limit is only there so the transaction is allowed to do its work, and so you can refuse a signature whose worst case you cannot afford.

The multiplication

Fee in MON equals gas times price per gas, and the price is in wei, which is 10^−18 MON. A base fee of 100 gwei is 100 × 10^−9 MON per gas. Times 350,000 gas, that is 0.035 MON. Times 550,000 gas, that is 0.055 MON. Times 21,000 gas, a plain transfer, that is 0.0021 MON. Those are the figures at a 100 gwei floor with a zero tip. If the base fee on the block is 2 gwei, divide by fifty. If your wallet adds a 50 gwei tip, add half again. Do the multiplication with the fee the wallet is about to sign, not with a dollar figure copied from a thread.

The docs’ dollar aside goes stale the hour MON moves. The MON figure does not. When you are deciding whether a 50 MON clip can pay for its own exit, 0.035 MON is the right unit. It is 0.07 percent of the clip. It is not a reason to avoid the chain, and it is not nothing if you are clipping 1 MON.

0.035 MON is the ceiling of a 350,000 gas sell at 100 gwei. The receipt is usually under it.

Why the limit is larger than the work

A swap’s real cost sits near a couple of hundred thousand gas when the path is a single hop and the token is already approved. The desk signs 350,000 on a wallet sell and 550,000 on a vault sell so a slightly longer path, or a cold token, does not revert for lack of gas after you have already decided to leave. Unused gas is not charged. A limit of 350,000 that uses 210,000 bills 210,000. The extra is permission, not a tip.

An estimate, eth_estimateGas, is a simulation of that permission. It is also a round trip to a node before the wallet opens. On a close, that round trip is the delay. The desk skips it and uses the fixed limit. If the simulation would have reverted, the chain will revert instead, and you will see a receipt rather than a spinner. That is a worse outcome only if you were using the spinner as a substitute for reading the price. You should already have read the price. It was on the card.

What to check on the prompt

The wallet shows a fee in MON that is limit times the fee it chose. If that fee is many times 0.035 MON, the wallet has invented a large tip or a large limit. Reject it and look. A close does not need a limit in the millions. It does not need a tip that rivals the clip. A fee of a few hundredths, or a few tenths if the base fee has lifted, is the shape of this trade. A fee of several MON is a different transaction, and you should not sign it to get out of a 50 MON position.

After it lands

Open the receipt. Read gas used, the effective price, and the product. That product is what left your address. Write it next to the fill if you are keeping score. The difference between the mark and the MON you received is slippage and the pool fee. The gas is extra, and it is small, and it is the only part that is about the chain rather than the pool. Do not let a blog’s dollar conversion from a different week tell you otherwise.