Calldata vs Memory

Last Updated on 24. March 2025 by Mario Oettler

If you are unaware of what calldata, memory and storage is, you an take a look here.

Calldata is an immutable, temporary location for function arguments.

Here is a code sample to demonstrate the difference in gas cost.

pragma solidity 0.8.29;

contract CallData{
    function callData(uint256[] calldata varA) public{

    }

    function memoryData(uint256[] memory varB) public{

    }
}

Operator	Gas Costs
callData	448
memory	1541

It is important to notice that calldata is immutable. Hence, it is impossible to alter values. The following code results in a compiler error as the member push() is not available for calldata.

    function callData(uint256[] calldata varA) public returns(uint256[] calldata){
        varA.push() = 5;
        return varA;
    }