getFeeForMessage

Learn getFeeForMessage use cases, code examples, request parameters, response structure, and tips.

The getFeeForMessage RPC method estimates the base transaction fee (in lamports) required to process a given compiled transaction message. This is especially helpful for displaying cost estimates to users or optimizing fee strategies before submitting transactions.

Version Note: This method is available in solana-core v1.9 and above. For older versions, use getFees.

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✅ Common Use Cases

• Estimate Transaction Fees Calculate the expected fee for a transaction before sending it to the network.

• Optimize Transaction Costs Compare fees across different transaction structures or times to identify cost-efficient strategies.

• Improve User Experience Show users a real-time fee estimate in your UI before they sign and submit a transaction.

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🛠 Request Parameters

getFeeForMessage takes the following parameters:

• message (string, required): A base64-encoded serialized Solana transaction message. Must be a valid compiled message containing instructions, fee payer, and recent blockhash.

• config (object, optional): Configuration object with:

  • commitment (string): Commitment level (processed, confirmed, or finalized). Defaults to finalized.

  • minContextSlot (number): The minimum slot at which the request is evaluated (for consistency in long-running processes).

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📦 Response Structure

The result field contains:

{
  "context": {
    "slot": <u64>
  },
  "value": <u64 | null>
}

• context.slot – The slot used when evaluating the fee.

• value – Estimated fee in lamports (1 SOL = 1,000,000,000 lamports). null if the fee could not be calculated (e.g., expired blockhash or invalid message).

💡 Example: Estimate Fee for a Simple Transfer

First, compile a transfer transaction and extract its message in base64 format, then call:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "getFeeForMessage",
  "params": [
    "base64_encoded_transaction_message_here",
    {
      "commitment": "finalized"
    }
  ]
}

Code Examples

Nodejs

const fetch = require('node-fetch');

async function getFeeForMessage(rpcUrl) {
  try {
    const response = await fetch(rpcUrl, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({
        jsonrpc: '2.0',
        id: 1,
        method: 'getFeeForMessage',
        "params": [
            "MESSAGE_BASE64_ENCODED", // Replace with your actual base64 encoded message
            { "commitment": "processed" }
          ]
      }),
    });

    const data = await response.json();
    
    // Print the exact full response
    console.log('Full RPC Response:');
    console.log(JSON.stringify(data, null, 2));
    
    return data;
  } catch (error) {
    console.error('Error getting health:', error.message);
    return null;
  }
}

// Example usage
const RPC_URL = 'https://rpc.coinvera.io/?x-api-key=your-coinvera-x-api-key';

getFeeForMessage(RPC_URL);

Python

Example Response

{
  "jsonrpc": "2.0",
  "result": {
    "context": { "slot": 5068 },
    "value": 5000
  },
  "id": 1
}

🧠 Developer Tips

• Message Construction Ensure your message is well-formed with:

  • Valid fee payer

  • Correct instructions

  • A recent blockhash (within ~2 minutes)

• Expired Blockhash If the blockhash is too old, the fee may return as null. Always refresh the blockhash before compiling the message.

• Base Fee Only This method returns only the base network fee. To estimate priority fees, use getRecentPrioritizationFees.

• Lamports, Not SOL The value is returned in lamports. Divide by 1_000_000_000 to convert to SOL for display purposes.

• Handling Null Responses A null fee indicates:

  • Invalid or expired blockhash

  • Malformed message

  • Inability to compute at current commitment level