In this article, we will describe the nuances of processing transactions in the L2 network.
How fast is a transaction, and when is it irreversible?
Blocks arrive every second. That inclusion, called a soft confirmation, is the sequencer's word only. Your transaction becomes "safe" when its batch is confirmed on Ethereum, within about 30 minutes, and "finalized" about 13 minutes after that. Only the finalized state is irreversible.
Confirmation stages
- Soft confirmation. Your transaction is included in an L2 block, on the sequencer's word. Typical time: about 1 second.
- Safe. The batch with your transaction is posted to and confirmed on Ethereum. Typical time: up to about 30 minutes.
- Finalized. Your transaction is backed by finalized Ethereum data and becomes irreversible. Typical time: about 13 minutes after the batch lands on Ethereum.
Flashblocks, partial blocks streamed ahead of each one-second block, are not enabled on Whitechain Mainnet or Whitechain Sepolia yet, and there is no Flashblocks stream to connect to. Once enabled, they will give faster feedback with the same trust as a soft confirmation. The confirmation stages above do not change.
Can an Ethereum reorg roll back the transaction?
A finalized L2 block is protected the same way finalized Ethereum blocks are, so a reorg does not roll it back. A shallow reorg can move the "safe" head: the node re-derives from the canonical Ethereum chain and the affected batch is re-posted. Blocks that reached finality cannot be rolled back.
Fees
Whitechain is configured in OP Stack custom gas token mode, with WBT as the native token instead of ETH. Every fee on the network is paid in WBT, regardless of what you are doing, so you need a WBT balance to send any transaction. Using WBT for gas means one asset covers both on-chain gas and exchange utility.
A fee has two parts: the L2 execution fee (the cost to run your transaction on Whitechain) and the L1 data fee (the cost to publish it to Ethereum).
At the 5 gwei base-fee floor, a plain WBT transfer of 21,000 gas costs about 0.000105 WBT to execute, well under one cent at an illustrative $50 per WBT. Deploying a small contract costs about 0.0006 WBT, roughly three cents at the same illustrative price.
Whitechain Mainnet uses the same L2 fee parameters as Whitechain Sepolia: a 5 gwei minimum base fee and no operator fee. The L1 data fee depends on Ethereum gas prices, so on Mainnet it is higher than on the testnet.
Please note: The explorer may show only the L2 execution fee. The L1 data fee for publishing your transaction to Ethereum is charged on top of it, and the difference between shown fee and your balance amount is that fee. Both parts are always charged.
FAQ
Do I pay for a transaction that fails?
Yes. The network does the work up to the point of failure, so you pay for the gas used, and both fee parts are charged.
How predictable are gas prices?
The L2 base fee follows EIP-1559 with elasticity 6 and denominator 100, so a full block raises it by 5%, an empty block lowers it by 1%, and it never drops below 5 gwei. The same parameters apply on Mainnet and Whitechain Sepolia. The variable part is the L1 data fee, which tracks Ethereum's base fee and blob base fee, so your total rises when Ethereum is busy.
Who receives the fees?
The protocol collects fees into on-chain fee vaults: the base fee, the priority tip, and the L1 data fee each go to a separate vault. The L1 data fee offsets the cost of posting data to Ethereum. Whitechain sets the operator fee to zero, so you pay the L2 execution cost and the L1 settlement cost only, with no extra surcharge.
How do I estimate a fee correctly?
You can use existing tooling. Libraries such as Viem include OP Stack support and return the L1 data fee for you, and they keep working across network upgrades. If you cannot use a library, read the L1 data fee from the “GasPriceOracle” predeploy at 0x420000000000000000000000000000000000000F by calling “getL1Fee” with your serialized, unsigned transaction. Do not implement the fee formula yourself; it changes with upgrades.