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# zkSync Gas Fee Guide
While ZK provides better user privacy and lower gas fees compared to Ethereum mainnet, the fees calculation mechanism in zkSync is different from Ethereum, Arbitrum or Optimism.
Users usually only spend a portion of the estimated transaction cost and they receive unused portions in the form of a refund.
At times, you may receive up to 70% of the fee cost with a refund. It is an automatic process and it is not controlled by users nor DerpDEX.
**Parameter to reduce Gas Limit**
This parameter is set automatically in the wallet when a transaction is called. For a more customized parameter, potentially, the user can set a 50% reduction to the gas limit (please experiment at your own risk).
**Default Setting**
**Experiment: Swapping 0.001 ETH for USDC**
*Please experiment at your own risk and may result in a failed transaction.*
Using the default settings, the transaction fee was $0.33 with breakdown of actual fees and refund.
Adjusting the default gas limit to **minimum value for successful transaction** i.e. 330,000 which is at least 7 times lower than the default value.
Upon performing the transaction, you will receive 0 refund and the transaction fees is 2 times lower than the original fees ($0.33).
The minor difference may sum up to a significant value if you are performing higher volume and value transactions.
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\&#xNAN;*Please experiment at your own risk and may result in a failed transaction.*
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Credits:
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