Arbitrum - invalid maxFeePerGas & maxPriorityFeePerGas values

[0xARK]

Ethers Version

5.5.3

Search Terms

arbitrum, maxFeePerGas, maxPriorityFeePerGas

Describe the Problem

I'm trying to make a simple swap on arbitrum between 2 tokens, and for that I detect automatically the maxFeePerGas and maxPriorityFeePerGas values to use in the transaction thanks to the ethers's function getFeeData()

At the time of this writing, arbitrum maxFeePer gas is 0.1, but the ethers function return a value of 2.5. This increase the cost of the transaction by 100.

Code Snippet

const ethers = require('ethers');

const test = async () => {
    let provider = new ethers.providers.JsonRpcProvider("https://arb1.arbitrum.io/rpc");
    let feeData = await provider.getFeeData();
    console.log(ethers.utils.formatUnits(feeData.maxFeePerGas, "wei")); // 2.7 instead of 0.2
    console.log(ethers.utils.formatUnits(feeData.maxPriorityFeePerGas, "wei")); // 2.5 instead of 0
}

test().then().catch(e => console.log(e));

Contract ABI

No response

Errors

No response

Environment

Altcoin - Please specify (e.g. Polygon)

Environment (Other)

Arbitrum

[0xARK]

It seems that this is due to these lines, since maxPriorityFeePerGas is equal to 0 on Arbitrum and some others blockchains supporting eip-1559 :

ethers.js/packages/abstract-provider/src.ts/index.ts

Lines 249 to 250 in 0578a88

	maxPriorityFeePerGas = BigNumber.from("2500000000");
	maxFeePerGas = block.baseFeePerGas.mul(2).add(maxPriorityFeePerGas);

Anyone have an idea to improve that ?

[ricmoo]

You can either subclass your provider (overriding the getFeeData to adjust for your desired priorityFee) or pass in an overriding value on each call.

There is no automatic way to get this, so the value is tuned for Ethereum.

In v6, each Network has the opportunity to select their own default value via a NetworkPlugin.

Make sense? :)

[0xARK]

Yes, I was thinking to reimplement this function, didn't think about override it, thank you for the idea :)

This v6 seems interesting, can't wait to see it 👀

[zzhengzhuo]

Sorry for disturbing.
But why not get maxPriorityFeePerGas by rpc eth_maxPriorityFeePerGas or estimate by eth_feeHistory ?

[0xARK]

Yeah, that's what I'm doing right now. But you must take in count that eth_feeHistory is not available on all blockchains and his estimation could be largely overpriced on some of them too.

[Holybasil]

Will ethers calculate maxPriorityFeePerGas and maxFeePerGas according to this specification?

[AndonMitev]

Hey did you manage to calculate fees for arbitrum? I'm trying by multiplying wallet.estimateGas * feeData.maxFeePerGas but is like very high maxFeePerGas: 1200000000, estimateGas: 489733 and when multiplied gives: 0.0005876796 eth for fee