Transaction Fees

The transaction fee for the current Klaytn virtual machine (KLVM) is computed as follows:

Transaction fee := (total gas used) x (unit price)

• The total gas used is computed by KLVM based on the gas cost of the opcode and the intrinsic gas cost.

• unit price is the price of gas defined in Klaytn.

This calculated transaction fee is subtracted from the sender's or enterprise account's balance, depending on the transaction.

Gas and Unit Price Overview

Gas

Every action that changes the state of the blockchain requires gas. When a node processes user's transaction such as sending KLAY, using ERC-20 tokens, or executing a contract, the user has to pay for the computation and storage usage. The amount of payment is decided by the amount of gas required.

Gas is a measuring unit representing how much calculation is needed to process the user's transaction.

Unit Price

Unit price is the price for a single gas. The unit price (also called gas price) is set in the system by the governance. It is currently set to 25 Gpeb (i.e., 25 x 10^9 peb) per gas and cannot be changed by user. The current value of the unit price can be obtained by calling the klay.gasPrice API.

In Ethereum, users set the gas price for each transaction, and miners choose which transactions to be included in their block to maximize their reward. It is something like bidding for limited resources. This approach has been working because it is market-based. However, the transaction cost fluctuates and often becomes too high to guarantee the execution.

To solve the problem, Klaytn is using a fixed unit price and the price can be adjusted by the governance council. This policy ensures that every transaction will be handled equally and be guaranteed to be executed. Therefore, users do not need to struggle to determine the right unit price.

Transaction Validation against Unit Price

Klaytn only accepts transactions with gas prices, which can be set by the user, that are equal to the unit price of Klaytn; it rejects transactions with gas prices that are different from the unit price in Klaytn.

Unit Price Error

The error message invalid unit price is returned when the gas price of a transaction is not equal to the unit price of Klaytn.

Transaction Replacement

Klaytn currently does not provide a way to replace a transaction using the unit price but may support different methods for the transaction replacement in the future. Note that in Ethereum, a transaction with a given nonce can be replaced by a new one with a higher gas price.

Klaytn's Gas table

Basically, Klaytn is keeping compatibility with Ethereum. So Klaytn's gas table is pretty similar with that of Ethereum. But because of the existence of unique features of Klaytn, there are several new constants for those features.

Common Fee

Item	Gas	Description
G_zero	0	Nothing paid for operations of the set Wzero
G_base	2	Amount of gas to pay for operations of the set Wbase
G_verylow	3	Amount of gas to pay for operations of the set Wverylow
G_low	5	Amount of gas to pay for operations of the set Wlow
G_mid	8	Amount of gas to pay for operations of the set Wmid
G_high	10	Amount of gas to pay for operations of the set Whigh
G_blockhash	20	Payment for BLOCKHASH operation
G_extcode	700	Amount of gas to pay for operations of the set Wextcode
G_balance	400	Amount of gas to pay for a BALANCE operation
G_sload	200	Paid for a SLOAD operation
G_jumpdest	1	Paid for a JUMPDEST operation
G_sset	20000	Paid for an SSTORE operation when the storage value is set to non-zero from zero
G_sreset	5000	Paid for an SSTORE operation when the storage value’s zeroness remains unchanged or is set to zero
G_sclear	15000	Refund given (added into refund counter) when the storage value is set to zero from non-zero
R_selfdestruct	24000	Refund given (added into refund counter) for self-destructing an account
G_selfdestruct	5000	Amount of gas to pay for a SELFDESTRUCT operation
G_create	32000	Paid for a CREATE operation
G_codedeposit	200	Paid per byte for a CREATE operation to succeed in placing code into state
G_call	700	Paid for a CALL operation
G_callvalue	9000	Paid for a non-zero value transfer as part of the CALL operation
G_callstipend	2300	A stipend for the called contract subtracted from Gcallvalue for a non-zero value transfer
G_newaccount	25000	Paid for a CALL or SELFDESTRUCT operation which creates an account
G_exp	10	Partial payment for an EXP operation
G_expbyte	50	Partial payment when multiplied by dlog256(exponent)e for the EXP operation
G_memory	3	Paid for every additional word when expanding memory
G_txcreate	32000	Paid by all contract-creating transactions
G_transaction	21000	Paid for every transaction
G_log	375	Partial payment for a LOG operation
G_logdata	8	Paid for each byte in a LOG operation’s data
G_logtopic	375	Paid for each topic of a LOG operation
G_sha3	30	Paid for each SHA3 operation
G_sha3word	6	Paid for each word (rounded up) for input data to a SHA3 operation
G_copy	3	Partial payment for *COPY operations, multiplied by words copied, rounded up
G_blockhash	20	Payment for BLOCKHASH operation
G_extcodehash	400	Paid for getting keccak256 hash of a contract's code
G_create2	32000	Paid for opcode CREATE2 which bahaves identically with CREATE but use different arguments

Precompiled Contracts

Precompiled contracts are special kind of contracts which usually perform complex cryptographic computations and are initiated by other contracts.

Item	Gas	Description
EcrecoverGas	3000	Perform ECRecover operation
Sha256BaseGas	60	Perform sha256 hash operation
Sha256PerWordGas	12	​
Ripemd160BaseGas	600	Perform Ripemd160 operation
Ripemd160PerWordGas	120	​
IdentityBaseGas	15	​
IdentityPerWordGas	3	​
ModExpQuadCoeffDiv	20	​
Bn256AddGas	500	Perform Bn256 elliptic curve operation
Bn256ScalarMulGas	40000	​
Bn256PairingBaseGas	100000	​
Bn256PairingPerPointGas	80000	​
VMLogBaseGas	100	Write logs to node's log file - Klaytn only
VMLogPerByteGas	20	Klaytn only
FeePayerGas	300	Get feePayer's address - Klaytn only
ValidateSenderGas	5000 per signature	Validate the sender's address and signature - Klaytn only

Total gas of those items which has XXXBaseGas and XXXPerWordGas (e.g. Sha256BaseGas, Sha256PerWordGas) are calculated as

TotalGas = XXXBaseGas + (number of words * XXXPerWordGas)

ValidateSenderGas have to be paid per signature basis.

TotalGas = number of signatures * ValidateSenderGas

Account-related Gas Table

Item	Gas	Description
TxAccountCreationGasPerKey	20000	Gas required for a key-pair creation
TxValidationGasPerKey	15000	Gas required for a key validation
TxGasAccountUpdate	21000	Gas required for an account update
TxGasFeeDelegated	10000	Gas required for a fee delegation
TxGasFeeDelegatedWithRatio	15000	Gas required for a fee delegation with ratio
TxGasCancel	21000	Gas required to cancel a transaction which has a same nonce
TxGasValueTransfer	21000	Gas required to transfer KLAY
TxGasContractExecution	21000	Base gas for contract execution
TxDataGas	100	Gas required per transaction's single byte

Gas for payload data is calculated as below

GasPayload = number_of_bytes * TxDataGas

Gas Formula for Transaction Types

TxType	Gas
LegacyTransaction	TxGas + PayloadGas + KeyValidationGas
ValueTransfer	TxGasValueTransfer + KeyValidationGas
ValueTransferMemo	TxGasValueTransfer + PayloadGas + KeyValidationGas
AccountUpdate	TxGasAccountUpdate + KeyCreationGas + KeyValidationGas
SmartContractDeploy	TxGasContractCreation + PayloadGas + KeyValidationGas
SmartContractExecution	TxGasContractExecution + PayloadGas + KeyValidationGas
Cancel	TxGasCancel + KeyValidationGas

KeyValidationGas is defined as below based on key type,

Key Type	Gas
Nil	N/A
Legacy	0
Fail	0
Public	0
MultiSig	(keys-1) * GasValidationPerKey (15000)
RoleBased	Based on keys in the role used in the validation

KeyCreationGas is defined as below based on key type,

Key Type	Gas
Nil	N/A
Legacy	0
Fail	0
Public	GasCreationPerKey (20000)
MultiSig	(keys) * GasCreationPerKey
RoleBased	Gas fee calculated based on keys in each role. e.g., GasRoleTransaction = (keys) GasCreationPerKey GasRoleAccountUpdate = (keys) GasCreationPerKey GasRoleFeePayer = (keys) * GasCreationPerKey