how to estimate bandwidth and get same value as on tronscan

[kricha]

how to estimate bandwidth and get same value as on tronscan

[svein1010]

You can calculate a unsigned transaction but the result is not the ultimate result. Only the signed transaction will be stored in the blockchain.

[svein1010]

In Java-tron, the consumed bandwidth of a transaction depends on its byte size after being serialized by protobuf.
In frontend, you can use the following function to calculate the bandwidth with a signedTransaction roughly:

function estimateBandwidth(signedTxn) {
    const DATA_HEX_PROTOBUF_EXTRA = 3;
    const MAX_RESULT_SIZE_IN_TX = 64;
    const A_SIGNATURE = 67;

    const len = signedTxn.raw_data_hex.length /2 + DATA_HEX_PROTOBUF_EXTRA + MAX_RESULT_SIZE_IN_TX  ;
    const signatureListSize = signedTxn.signature.length || 0;
    for(let i=0;i<signatureListSize;i++)
    {
        len += A_SIGNATURE;
    }
    return len;
}

[kricha]

In Java-tron, the consumed bandwidth of a transaction depends on its byte size after being serialized by protobuf. In frontend, you can use the following function to calculate the bandwidth with a signedTransaction roughly:

function estimateBandwidth(signedTxn) {
    const DATA_HEX_PROTOBUF_EXTRA = 3;
    const MAX_RESULT_SIZE_IN_TX = 64;
    const A_SIGNATURE = 67;

    const len = signedTxn.raw_data_hex.length /2 + DATA_HEX_PROTOBUF_EXTRA + MAX_RESULT_SIZE_IN_TX  ;
    const signatureListSize = signedTxn.signature.length || 0;
    for(let i=0;i<signatureListSize;i++)
    {
        len += A_SIGNATURE;
    }
    return len;
}

before signing I can't calculate this?

[kricha]

You can calculate a unsigned transaction but the result is not the ultimate result. Only the signed transaction will be stored in the blockchain.

thanks