# EIP-1559 & Gas Estimation 

**Published by:** [taihucao](https://paragraph.com/@taihucao/)
**Published on:** 2023-04-10
**URL:** https://paragraph.com/@taihucao/eip-1559-gas-estimation

## Content

EIP-155 Replay Attack Protection ChainID https://chainlist.org/ EIP-1559 (London) https://eips.ethereum.org/EIPS/eip-1559 Why EIP-1559? Background: ETH token-nomic (Inflation, Deflation) Miner income Block Reward (also, Uncle Block Reward) Transaction Fee (Gas) -- reached nearly half of Block Reward - Security Issue MEV Issues Gas War Congestion Security threat by Miners Mainly About Base Fee -- Burn Priority Fee -- Miner Max Fee -- Remaining Part will be refund to sender Transactions on explorer Legacy TX: https://etherscan.io/tx/0x177767d9398486c932d8b1e289e55a8e3b843a381b7470920a4339de775f4c0f EIP-1559 TX: https://etherscan.io/tx/0x84c1a231c787cd3b4f031cfeb6a1d66bfb0a6e226e438e3accfda7be49e4cd6b Remaining Issues Gas War NO Gas CELING How to set up gas provider for EIP-1559? Sample Code with Web3j: // Get baseFee from last block BigInteger baseFeePerGas = web3j.ethGetBlockByNumber(DefaultBlockParameterName.LATEST, false).send().getBlock().getBaseFeePerGas(); BigInteger maxPriorityFeePerGas = web3j.ethMaxPriorityFeePerGas().send().getMaxPriorityFeePerGas(); BigInteger maxFeePerGas = baseFeePerGas.add(maxPriorityFeePerGas); Gas Estimation What and Why? Before the execution, would like to how much gas the transaction need to get successfully executed. For better gas preparation; For more reasonable fee structure; For avoid most TX execution failures; etc. How? Sample Code with Web3j: private static ContractEIP1559GasProvider buildGasProviderForApprove(Web3j web3j, String fromAddress, String scAddress, String spender, BigInteger amountInWei) throws IOException { long chainId = web3j.ethChainId().send().getChainId().longValue(); BigInteger baseFeePerGas = web3j.ethGetBlockByNumber(DefaultBlockParameterName.LATEST, false).send().getBlock().getBaseFeePerGas(); BigInteger maxPriorityFeePerGas = web3j.ethMaxPriorityFeePerGas().send().getMaxPriorityFeePerGas(); BigInteger maxFeePerGas = baseFeePerGas.add(maxPriorityFeePerGas); BigInteger gasLimit = estimateApproveGasLimit(web3j, fromAddress, scAddress, spender, amountInWei, maxFeePerGas, maxPriorityFeePerGas); return new StaticEIP1559GasProvider(chainId, maxFeePerGas, maxPriorityFeePerGas, gasLimit); } private static BigInteger estimateApproveGasLimit(Web3j web3j, String fromAddress, String scAddress, String spender, BigInteger amountInWei, BigInteger maxFeePerGas, BigInteger maxPriorityFeePerGas) throws IOException { Function function = new org.web3j.abi.datatypes.Function( "approve", Arrays.<Type>asList(new org.web3j.abi.datatypes.Address(160, spender), new org.web3j.abi.datatypes.generated.Uint256(amountInWei)), Collections.<TypeReference<?>>emptyList()); EthGetTransactionCount ethGetTransactionCount = web3j.ethGetTransactionCount(fromAddress, DefaultBlockParameterName.PENDING).send(); BigInteger nonce = ethGetTransactionCount.getTransactionCount(); long chainId = web3j.ethChainId().send().getChainId().longValue(); Transaction transaction = new Transaction(fromAddress, nonce, null, BigInteger.valueOf(4300000), scAddress, BigInteger.ZERO, FunctionEncoder.encode(function), chainId, maxPriorityFeePerGas, maxFeePerGas); BigInteger gasLimit = web3j.ethEstimateGas(transaction).send().getAmountUsed(); return gasLimit; }

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