> For the complete documentation index, see [llms.txt](https://bridge-docs.orbitchain.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://bridge-docs.orbitchain.io/faq/gas-fee-guide-en.md). # Gas Fee Guide \[EN] Most blockchains require a gas fee to process a transaction. A Gas fee is the fee received from the blockchain and is generated separately from Orbit Bridge fees (Tax, Bridge Fee). If the gas fee occurs in the chain of the asset you want to convert (From chain), you must always have a native token at some cost in your wallet to proceed with the coin conversion normally. The following transactions usually occur for token conversion: * **Contract approval (approve) transaction** * **Transactions for final token conversion** For assets that are converted for the first time, approval is required for the transaction with a first-time contract call and a new address. This has to be done only once for each token. When it is completed, a ‘transaction for final coin conversion’ proceeds, and the gas fee is required. As such, a maximum of 2 consecutive transactions can be performed per bridge gun, so we recommend that you have enough assets in your wallet to use as gas fees in advance. In general, the gas fee required for each chain is as follows. #### **Estimated Gas Fee by Blockchain** * ORBIT: 0 ORC * ETHEREUM: 0.003647417870370370 ETH (\*\* **0.003 \~ 0.004 ETH**) * KLAYTN: 0.0025644140499999817 KLAY (\*\* **1\~2 KLAY**) * BNB: 0.00038354894337000293 BNB (\*\* **0.001\~0.003 BNB**) * POLYGON: 0.004929315292312894 MATIC * HECO: 0.0003918617557500031 HT * CELO: 0.00004307683999999999 CELO * XDAI: 0.00019813539043626402 XDAI \*\* () brackets are the recommended holding quantity calculated based on the average gas fee of 1,000 recent bridge transactions (As of 2022-07-13). As the congestion level of the chain increases, the gas fee rises in real-time, so even if you have the recommended quantity, it may not be possible to proceed with the transaction. In that case, please check the Gas Tracker page for each chain below. In particular, since the gas fee fluctuates severely for ETHEREUM, POLYGON, and FANTOM chains, it is recommended that you check the gas tracker site and reserve a sufficient amount of gas fee if you cannot request a transaction. #### **Gas Tracker Guide by Blockchain** * ETHEREUM: * KLAYTN: * BNB: * POLYGON: * FANTOM: * HECO: * CELO: [https://explorer.bitquery.io/celo\_rc1/gas]() * AVALANCHE: * MOONRIVER: --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://bridge-docs.orbitchain.io/faq/gas-fee-guide-en.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.