Priority Fee & Simulation APIs

Use getRecentPrioritizationFees, simulateTransaction, and provider fee APIs to estimate compute units and priority fees before sending transactions.

Recipe

Quick-reference recipe card - copy-paste ready.

import { createSolanaRpc, getBase64EncodedWireTransaction } from "@solana/kit";
 
const rpc = createSolanaRpc("https://api.mainnet-beta.solana.com");
 
await rpc.getRecentPrioritizationFees([]).send();
await rpc.simulateTransaction(encodedTx, {
  commitment: "processed",
  sigVerify: false,
}).send();

When to reach for this:

Setting dynamic priority fees from recent network percentiles.
Estimating CU consumption to set compute budget instructions.
Preflight checking custom program errors without landing.
Debugging transaction failures in staging.

Working Example

import { createSolanaRpc } from "@solana/kit";
 
const rpc = createSolanaRpc(process.env.RPC_URL!);
 
// Recent priority fees for relevant accounts (empty = global sample)
const fees = await rpc.getRecentPrioritizationFees([]).send();
const recent = fees.map((f) => f.prioritizationFee).filter((n) => n > 0);
recent.sort((a, b) => a - b);
const p75 = recent[Math.floor(recent.length * 0.75)] ?? 0;
console.log("suggested microLamports CU price (p75):", p75);
 
// Simulate signed or partially signed tx (base64 wire)
const simulation = await rpc
  .simulateTransaction("BASE64_WIRE_TX", {
    commitment: "processed",
    sigVerify: false,
    replaceRecentBlockhash: true,
  })
  .send();
 
console.log("err:", simulation.value.err);
console.log("units:", simulation.value.unitsConsumed);
console.log("logs:", simulation.value.logs?.slice(0, 5));

What this demonstrates:

Priority fee RPC samples recent landed transactions for fee guidance.
Simulation returns unitsConsumed and logs without committing state (except when configured).
replaceRecentBlockhash helps simulate txs with expiring blockhashes.

Deep Dive

How It Works

Priority fees are micro-lamports per compute unit paid to validators on top of base fee.
getRecentPrioritizationFees returns per-slot fee observations for account lock sets.
simulateTransaction runs SVM against bank snapshot at chosen commitment.
Providers may expose enhanced priorityFeeEstimate endpoints with percentile stats.

Simulation Options

Option	Effect
`sigVerify: false`	Faster sim, skips signature checks
`replaceRecentBlockhash`	Refreshes blockhash for stale txs
`innerInstructions`	Returns CPI breakdown
`accounts`	Returns post-simulation account states

TypeScript Notes

// After simulation, set compute budget ix with headroom
const units = simulation.value.unitsConsumed ?? 200_000;
const limit = Math.ceil(units * 1.1);
const microLamports = Math.max(p75, 1_000);

Gotchas

Simulation success ≠ landing - congestion and expired blockhashes still fail on send. Fix: combine with fresh blockhash and priority fee retries.
Underpriced priority fee - simulation passes but tx drops. Fix: target 75th-90th percentile with cap.
sigVerify false hiding signer errors - false positives. Fix: final preflight with sigVerify: true before mainnet send.
Stale prioritization sample - fees spike during NFT mints. Fix: refresh fees per send batch.
Ignoring unitsConsumed - default 200k CU limit may be too low. Fix: set explicit limit from simulation + 10% headroom.

Alternatives

Alternative	Use When	Don't Use When
Fixed priority fee	Low traffic devnet	Mainnet congestion periods
Jito tip APIs	Bundle landing	Simple transfers
Surfpool simulate	Fork-accurate DeFi	Wallet-only apps
CLI `solana confirm -v`	Post-send debug	Pre-send planning

FAQs

What units does prioritizationFee use?

Micro-lamports per compute unit for priority fee instruction - multiply by requested CU budget for total priority lamports.

How often to refresh fees?

Per transaction batch during congestion; less frequent on quiet devnet.

Does simulateTransaction cost SOL?

No on-chain spend - RPC compute only; some providers rate-limit heavy simulation.

Can I simulate without all signers?

Often yes with sigVerify: false - useful for partial signing flows.

How does this relate to compute budget program?

Simulation informs SetComputeUnitLimit and SetComputeUnitPrice instruction values.

Do provider fee APIs differ?

Helius and others wrap percentile estimates - fall back to getRecentPrioritizationFees for portability.

Why simulate with processed commitment?

Fastest feedback during iterative debugging - match send commitment for final checks.

Can simulation detect slippage failures?

Yes if program returns error on insufficient output - read logs and err field.

Does kit 7.0.0 encode wire txs?

Use getBase64EncodedWireTransaction when building txs with kit pipelines before simulate.

Where is landing policy documented?

See Setting Priority Fees and Estimating Compute Units.

Estimating Compute Units - CU headroom
Setting Priority Fees - fee strategy
Simulating Transactions - conceptual model
RPC Providers - enhanced APIs

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.

Priority Fee & Simulation APIs

Use getRecentPrioritizationFees, simulateTransaction, and provider fee APIs to estimate compute units and priority fees before sending transactions.

Recipe

Quick-reference recipe card - copy-paste ready.

import { createSolanaRpc, getBase64EncodedWireTransaction } from "@solana/kit";
 
const rpc = createSolanaRpc("https://api.mainnet-beta.solana.com");
 
await rpc.getRecentPrioritizationFees([]).send();
await rpc.simulateTransaction(encodedTx, {
  commitment: "processed",
  sigVerify: false,
}).send();

When to reach for this:

Setting dynamic priority fees from recent network percentiles.
Estimating CU consumption to set compute budget instructions.
Preflight checking custom program errors without landing.
Debugging transaction failures in staging.

Working Example

import { createSolanaRpc } from "@solana/kit";
 
const rpc = createSolanaRpc(process.env.RPC_URL!);
 
// Recent priority fees for relevant accounts (empty = global sample)
const fees = await rpc.getRecentPrioritizationFees([]).send();
const recent = fees.map((f) => f.prioritizationFee).filter((n) => n > 0);
recent.sort((a, b) => a - b);
const p75 = recent[Math.floor(recent.length * 0.75)] ?? 0;
console.log("suggested microLamports CU price (p75):", p75);
 
// Simulate signed or partially signed tx (base64 wire)
const simulation = await rpc
  .simulateTransaction("BASE64_WIRE_TX", {
    commitment: "processed",
    sigVerify: false,
    replaceRecentBlockhash: true,
  })
  .send();
 
console.log("err:", simulation.value.err);
console.log("units:", simulation.value.unitsConsumed);
console.log("logs:", simulation.value.logs?.slice(0, 5));

What this demonstrates:

Priority fee RPC samples recent landed transactions for fee guidance.
Simulation returns unitsConsumed and logs without committing state (except when configured).
replaceRecentBlockhash helps simulate txs with expiring blockhashes.

Deep Dive

How It Works

Priority fees are micro-lamports per compute unit paid to validators on top of base fee.
getRecentPrioritizationFees returns per-slot fee observations for account lock sets.
simulateTransaction runs SVM against bank snapshot at chosen commitment.
Providers may expose enhanced priorityFeeEstimate endpoints with percentile stats.

Simulation Options

Option	Effect
`sigVerify: false`	Faster sim, skips signature checks
`replaceRecentBlockhash`	Refreshes blockhash for stale txs
`innerInstructions`	Returns CPI breakdown
`accounts`	Returns post-simulation account states

TypeScript Notes

// After simulation, set compute budget ix with headroom
const units = simulation.value.unitsConsumed ?? 200_000;
const limit = Math.ceil(units * 1.1);
const microLamports = Math.max(p75, 1_000);

Gotchas

Simulation success ≠ landing - congestion and expired blockhashes still fail on send. Fix: combine with fresh blockhash and priority fee retries.
Underpriced priority fee - simulation passes but tx drops. Fix: target 75th-90th percentile with cap.
sigVerify false hiding signer errors - false positives. Fix: final preflight with sigVerify: true before mainnet send.
Stale prioritization sample - fees spike during NFT mints. Fix: refresh fees per send batch.
Ignoring unitsConsumed - default 200k CU limit may be too low. Fix: set explicit limit from simulation + 10% headroom.

Alternatives

Alternative	Use When	Don't Use When
Fixed priority fee	Low traffic devnet	Mainnet congestion periods
Jito tip APIs	Bundle landing	Simple transfers
Surfpool simulate	Fork-accurate DeFi	Wallet-only apps
CLI `solana confirm -v`	Post-send debug	Pre-send planning

FAQs

What units does prioritizationFee use?

Micro-lamports per compute unit for priority fee instruction - multiply by requested CU budget for total priority lamports.

How often to refresh fees?

Per transaction batch during congestion; less frequent on quiet devnet.

Does simulateTransaction cost SOL?

No on-chain spend - RPC compute only; some providers rate-limit heavy simulation.

Can I simulate without all signers?

Often yes with sigVerify: false - useful for partial signing flows.

How does this relate to compute budget program?

Simulation informs SetComputeUnitLimit and SetComputeUnitPrice instruction values.

Do provider fee APIs differ?

Helius and others wrap percentile estimates - fall back to getRecentPrioritizationFees for portability.

Why simulate with processed commitment?

Fastest feedback during iterative debugging - match send commitment for final checks.

Can simulation detect slippage failures?

Yes if program returns error on insufficient output - read logs and err field.

Does kit 7.0.0 encode wire txs?

Use getBase64EncodedWireTransaction when building txs with kit pipelines before simulate.

Where is landing policy documented?

See Setting Priority Fees and Estimating Compute Units.

Estimating Compute Units - CU headroom
Setting Priority Fees - fee strategy
Simulating Transactions - conceptual model
RPC Providers - enhanced APIs

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.

Priority Fee & Simulation APIs

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Priority Fee & Simulation APIs