How to Fix Arbitrum Gas Estimation Failed and Underpriced Errors
Arbitrum's fee model is not the same as Ethereum's. That difference causes most of the gas-related errors users encounter. Understanding the two components is the first step to fixing them.
Arbitrum charges for two things: L2 execution gas and L1 calldata posting. The execution gas covers the computation that happens on Arbitrum's own chain. The calldata fee pays for posting your transaction data to Ethereum's L1. This second fee is the one that trips people up, because it is unpredictable. It depends on L1 congestion, not just L2 activity.
When your wallet estimates the total gas, it can misjudge the L1 portion. That is when you see "gas estimation failed" or "transaction underpriced."
Why gas estimation fails
The wallet attempts to simulate the transaction. It calculates the execution gas and estimates the L1 calldata cost. But the L1 base fee can shift between the estimation and the actual submission. If it rises, your prepared gas is suddenly too low, and the node rejects the transaction.
This is not a bug. It is a property of a rollup that posts data to a volatile base layer. The error is more common during periods of high L1 activity.
How to Set a Manual Gas Limit in MetaMask
MetaMask lets you override the automatic estimate. Open the transaction confirmation screen and look for "Advanced" or "Edit" near the gas section. Switch from the default "Market" to "Advanced" or "Custom."
Enter a higher gas limit. A safe rule is 1.5 to 2 times the estimated amount. For a typical swap or transfer, try 150,000 to 300,000. For contract interactions, 500,000 to 1,000,000 is often safer. The unused gas is refunded, so overestimating costs only the calldata fee.
The more important field is the max fee per gas. Set this to a value that covers both the execution and the L1 cost. Arbitrum's documentation recommends a max fee of at least 0.1 gwei above the current network base fee. During congestion, 0.2 to 0.5 gwei above is prudent.
MaxSubmissionCost and rabby wallet
Rabby Wallet exposes a parameter that MetaMask hides: maxSubmissionCost. This is the maximum you are willing to pay for the L1 calldata posting. If the estimate is too low, Rabby will show a warning and let you adjust it.
Navigate to the transaction confirmation screen. Find the "Advanced" tab. Look for a field labeled "Max submission cost" or "L1 calldata limit." Increase it by 10 to 20 percent. The exact number depends on the current L1 base fee, but a reasonable default is 0.001 to 0.01 ETH. Set it higher if you are transacting during an L1 fee spike.
If Rabby shows "gas estimation failed," it usually means the max submission cost is too low. Bump it until the warning disappears.
Fixing "Transaction Underpriced"
This error means the gas price you set is below the node's minimum relay price. On Arbitrum, that minimum can be higher than on Ethereum because the sequencer must cover its L1 costs.
The fix is straightforward: increase the max fee per gas. In MetaMask, open the transaction details, click "Speed up" or "Cancel," and set the new max fee to at least 0.1 gwei higher than the last attempt. In Rabby, use the "Resubmit" feature and raise the max fee by 0.2 to 0.5 gwei.
If the transaction is stuck and cannot be sped up, you may need to cancel it. Send a new transaction with the same nonce and a gas price of 0 ETH. Set the max fee per gas to 0.1 gwei or higher. This will replace the stuck transaction.
"Insufficient Funds for Gas"
Arbitrum requires ETH for gas. You cannot pay gas in USDC or other tokens. The wallet checks your ETH balance before sending. If it is too low, you get this error.
Check your balance. You need enough ETH to cover the execution gas plus the L1 calldata fee. The L1 portion can be significant. During high congestion, the calldata cost can exceed the execution cost by 10x or more. A simple transfer might require 0.005 to 0.01 ETH, while a complex DeFi interaction might need 0.02 to 0.05 ETH.
Bridge more ETH to Arbitrum if you are short. Do not try to lower the gas limit below the recommended minimum. That will cause the transaction to fail, and you will lose the fees anyway.
When to Wait
Sometimes the best fix is to wait. L1 gas fees are volatile. If the error is caused by a temporary spike, the transaction will go through once the L1 base fee drops. Check the current L1 gas price on Etherscan. If it is above 100 gwei, consider waiting an hour. If it is above 200 gwei, wait longer.
Arbitrum's sequencer processes transactions in order. If yours fails, you can resubmit it. The failed transaction's nonce is consumed, so you will need to send a new transaction with a higher nonce.
Summary
Gas estimation and underpriced errors on Arbitrum come from the two-component fee model. Set a manual gas limit 1.5x to 2x the estimate. Increase the max fee per gas by 0.1 to 0.5 gwei above the network base. In Rabby, adjust the max submission cost. Ensure you have enough ETH to cover both components. If all else fails, wait for L1 congestion to subside.
These steps work for MetaMask and Rabby Wallet. The same principles apply to other wallets that support Arbitrum.
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