Intrinsic Gas

Gas is a sum of IntrinsicGas and ExecutionGas. In here, we would focus on how IntrinsicGas is organized.

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Intrinsic gas related hardfork changes can be found at the bottom of this page. Go to Hardfork Changes.

Overview

A transaction's intrinsicGas can be calculated by adding up the next four factors.

IntrinsicGasCost = KeyCreationGas + KeyValidationGas + PayloadGas + TxTypedGas

• PayloadGas is calculated based on the size of the data field in the tx.
• KeyCreationGas is calculated when the transaction registers new keys. Only applicable in accountUpdate transaction.
• KeyValidationGas is calculated based on the number of signatures.
• TxTypedGas is defined based on the transaction types.

Before we get into the detail, keep in mind that not all key types apply the keyGases (KeyCreationGas and KeyValidationGas).

Key Type	Are those keyGases applicable?
Nil	No
Legacy	No
Fail	No
Public	Yes
MultiSig	Yes
RoleBased	Depending on key types in the role

KeyCreationGas

The KeyCreationGas is calculated as (number of registering keys) x TxAccountCreationGasPerKey (20000).
Please keep in mind that Public key type always has only one registering key, so the gas would be always 20000.

KeyValidationGas

KeyValidationGas is calculated as (number of signatures - 1) x TxValidationGasPerKey(15000).
Please keep in mind that Public key type always has only one signature key, so the gas would be always zero.

A Kaia transaction can also have a feePayer, so the total KeyValidationGas is like this.

KeyValidationGas = (KeyValidationGas for a sender) + (KeyValidationGas for a feePayer)

PayloadGas

Basically, PayloadGas is charged with number_of_bytes_of_tx_input x TxDataGas (100).

In the case of a transaction creating contract, an additional charge of number_of_words_of_initcode x InitCodeWordGas (2) is applied. It is effective since Shanghai hardfork.

TxTypedGas

There are three types of transactions in klaytn; base, feeDelegated, and feeDelegatedWithFeeRatio.

For example,

• TxTypeValueTransfer is the base type of the valueTransaction transaction.
• TxTypeFeeDelegatedValueTransfer is a feeDelegated type of the valueTransfer transaction.
• TxTypeFeeDelegatedValueTransferWithRatio is a feeDelegatedWithRatio type of the valueTransfer transaction.

This is important when calculating TxTypedGas:

• First, check the TxType is feeDelegated or feeDelegatedWithFeeRatio.
  • If the TxType is feeDelegated, add TxGasFeeDelegated(10000) to TxTypedGas
  • If the TxType is feeDelegatedWithFeeRatio, add TxGasFeeDelegatedWithRatio (15000) to TxTypedGas
• Second, check the transaction creates contract or not.
  • If the transaction creates contract, add TxGasContractCreation (53000) to TxTypedGas.
  • Otherwise, add TxGas (21000) to TxTypedGas.

For example,

• If it's legacyTransaction and creates contract, the TxTypedGas would be 0 + TxGasContractCreation(53000).
• If it's TxTypeFeeDelegatedValueTransfer, the TxTypedGas would be TxGasFeeDelegated(10000) + TxGas (21000)
• If it's TxTypeFeeDelegatedSmartContractDeployWithRatio, the TxTypedGas would be TxGasFeeDelegatedWithRatio (15000) + TxGasContractCreation (53000)

Hardfork changes

Hardfork	Change
Shanghai EVM	limit and meter initcode when calculating intrinsicGas - started to add 2 gas per word of the initcode
Istanbul EVM	make the PayloadGas of legacyTxType consistent with other TxTypes - Before: PayloadGas=number_of_zero_bytes_of_tx_input x 4 + number_of_nonzero_bytes_of_tx_input x 68 - After: PayloadGas=number_of_bytes_of_tx_input x 100 change keyValidationGas calculation logic - Before: KeyValidationGas=(number of keys - 1) x 15,000 - After: KeyValidationGas=(number of signatures - 1) x 15,000