🚥Priority Fee API

What Are Priority Fees on Solana?

Priority fees are an optional fee you can add to your transactions to incentivize block producers (leaders) to include your transaction in the next block. Priority fees are priced in micro-lamports per compute unit. It is recommended to include a priority fee in your transactions, but how much should you pay?

Helius Priority Fee API

The getPriorityFeeEstimate is a new RPC method that provides fee recommendations based on historical data. Most importantly, it considers both global and local fee markets.

For example, say you wanted to submit a swap on Jupiter. You could make the following request:

{
    "jsonrpc": "2.0",
    "id": "helius-example",
    "method": "getPriorityFeeEstimate",
    "params": [{
        "accountKeys": ["JUP6LkbZbjS1jKKwapdHNy74zcZ3tLUZoi5QNyVTaV4"],
        "options": {
            "recommended": true
        }
    }]
}

And the API will provide you with a recommended fee:

{
    "jsonrpc": "2.0",
    "result": {
        "priorityFeeEstimate": 33549.0
    },
    "id": "helius-example"
}

The estimate is priced in micro-lamports per compute unit.

You can also provide a serialized transaction instead of manually specifying the accounts. For example:

{
    "jsonrpc": "2.0",
    "id": "helius-example",
    "method": "getPriorityFeeEstimate",
    "params": [{
        "transaction": "AtP+61DWChFJcicQqntFaf...",
        "options": {
            "recommended": true,
            "transactionEncoding": "base64"
        }
    }]
}

How it Works

The method uses a set of predefined priority levels (percentiles) to dictate the returned estimate. Users can optionally specify to receive all the priority levels and adjust the window with which these are calculated via lookbackSlots

fn get_recent_priority_fee_estimate(request: GetPriorityFeeEstimateRequest) -> GetPriorityFeeEstimateResponse

struct GetPriorityFeeEstimateRequest {
  transaction: Option<String>,   // estimate fee for a serialized txn
  account_keys: Option<Vec<String>>, // estimate fee for a list of accounts
  options: Option<GetPriorityFeeEstimateOptions>
}

struct GetPriorityFeeEstimateOptions {
	priority_level: Option<PriorityLevel>, // Default to MEDIUM
	include_all_priority_fee_levels: Option<bool>, // Include all priority level estimates in the response
	transaction_encoding: Option<UiTransactionEncoding>, // Default Base58
	lookback_slots: Option<u8>, // The number of slots to look back to calculate the estimate. Valid numbers are 1-150, default is 150
	recommended: Option<bool>, // The Helius recommended fee for landing transactions
	include_vote: Option<bool>, // Include vote transactions in the priority fee estimate calculation. Default to true 
}

enum PriorityLevel {
	MIN, // 0th percentile
	LOW, // 25th percentile
	MEDIUM, // 50th percentile
	HIGH, // 75th percentile
	VERY_HIGH, // 95th percentile
  // labelled unsafe to prevent people from using and draining their funds by accident
	UNSAFE_MAX, // 100th percentile 
	DEFAULT, // 50th percentile
}

struct GetPriorityFeeEstimateResponse {
  priority_fee_estimate: Option<MicroLamportPriorityFee>
  priority_fee_levels: Option<MicroLamportPriorityFeeLevels>
}

type MicroLamportPriorityFee = f64

struct MicroLamportPriorityFeeLevels {
	min: f64,
	low: f64,
	medium: f64,
	high: f64,
	very_high: f64,
	unsafe_max: f64,
}

Examples

Request all priority fee levels for Jup v6

{
    "jsonrpc": "2.0",
    "id": "1",
    "method": "getPriorityFeeEstimate",
    "params": [{
        "accountKeys": ["JUP6LkbZbjS1jKKwapdHNy74zcZ3tLUZoi5QNyVTaV4"],
        "options": {
            "includeAllPriorityFeeLevels": true
        }
    }]
}

Response

{
    "jsonrpc": "2.0",
    "result": {
        "priorityFeeLevels": {
            "min": 0.0,
            "low": 2.0,
            "medium": 10082.0,
            "high": 100000.0,
            "veryHigh": 1000000.0,
            "unsafeMax": 50000000.0
        }
    },
    "id": "1"
}

Request the high priority level for Jup v6

{
    "jsonrpc": "2.0",
    "id": "1",
    "method": "getPriorityFeeEstimate",
    "params": [{
        "accountKeys": ["JUP6LkbZbjS1jKKwapdHNy74zcZ3tLUZoi5QNyVTaV4"],
        "options": {
            "priority_level": "HIGH"
        }
    }]
}

Response

{
    "jsonrpc": "2.0",
    "result": {
        "priorityFeeEstimate": 1200.0
    },
    "id": "1"
}

Sending a transaction with the Priority Fee API (Javascript)

This code snippet showcases how one can transfer SOL from one account to another. In this code, the transaction is passed to the priority fee API which then determines the specified priority fee from all the accounts involved in the transaction.

const {
  Connection,
  SystemProgram,
  Transaction,
  sendAndConfirmTransaction,
  Keypair,
  ComputeBudgetProgram,
} = require("@solana/web3.js");
const bs58 = require("bs58");

const HeliusURL = "https://mainnet.helius-rpc.com/?api-key=<YOUR_API_KEY>";
const connection = new Connection(HeliusURL);
const fromKeypair = Keypair.fromSecretKey(Uint8Array.from("[Your secret key]")); // Replace with your own private key
const toPubkey = "CckxW6C1CjsxYcXSiDbk7NYfPLhfqAm3kSB5LEZunnSE"; // Replace with the public key that you want to send SOL to

async function getPriorityFeeEstimate(priorityLevel, transaction) {
  const response = await fetch(HeliusURL, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({
      jsonrpc: "2.0",
      id: "1",
      method: "getPriorityFeeEstimate",
      params: [
        {
          transaction: bs58.encode(transaction.serialize()), // Pass the serialized transaction in Base58
          options: { priorityLevel: priorityLevel },
        },
      ],
    }),
  });
  const data = await response.json();
  console.log(
    "Fee in function for",
    priorityLevel,
    " :",
    data.result.priorityFeeEstimate
  );
  return data.result;
}
async function sendTransactionWithPriorityFee(priorityLevel) {
  const transaction = new Transaction();
  const transferIx = SystemProgram.transfer({
    fromPubkey: fromKeypair.publicKey,
    toPubkey,
    lamports: 100,
  });
  transaction.add(transferIx);

  transaction.recentBlockhash = (
    await connection.getLatestBlockhash()
  ).blockhash;
  transaction.sign(fromKeypair);

  let feeEstimate = { priorityFeeEstimate: 0 };
  if (priorityLevel !== "NONE") {
    feeEstimate = await getPriorityFeeEstimate(priorityLevel, transaction);
    const computePriceIx = ComputeBudgetProgram.setComputeUnitPrice({
      microLamports: feeEstimate.priorityFeeEstimate,
    });
    transaction.add(computePriceIx);
  }

  try {
    const txid = await sendAndConfirmTransaction(connection, transaction, [
      fromKeypair,
    ]);
    console.log(`Transaction sent successfully with signature ${txid}`);
  } catch (e) {
    console.error(`Failed to send transaction: ${e}`);
  }
}

sendTransactionWithPriorityFee("High"); // Choose between "Min", "Low", "Medium", "High", "VeryHigh", "UnsafeMax"

(Appendix) Calculating the Percentiles

To calculate the percentiles, we need to consider the global and local fee market over transactions in the last N slots

For example,

priority_estimate(p: Percentile, accounts: Accounts) = 
	max(percentile(txn_fees, p), percentile(account_fees(accounts), p))

where txn_fees are the txn_fees from the last 150 blocks, and account_fees(accounts) are the fees for transactions containing these accounts from the last 150 blocks. Here, we are considering the total set of fees seen for accounts and transactions as opposed to the minimum.

Global Fee Market Estimate

The global fee market estimate is a percentile of priority fees paid for transactions in the last N slots.

Local Fee Market Estimate

The local fee market is influenced by the number of people trying to obtain a lock on an account. We can estimate this similarly to the global fee market but instead use the percentile of fees paid for transactions involving a given account(s). If a user requests an estimate for multiple accounts in the same transaction, we will take the max of the percentiles across those accounts.

Priority Fee Estimate

The priority_fee_estimate will be the max of the global and local fee market estimates.

Extensions

This method could also be integrated into simulateTransaction and returned with the response context. This way, developers using simulateTransaction can eliminate an extra RPC call.