Rent & Rent-Exemption

Solana accounts must hold enough lamports to be rent-exempt - a one-time deposit based on data size. Without it, accounts cannot persist on-chain.

Recipe

solana rent 200

const rent = await rpc.getMinimumBalanceForRentExemption(200n).send();

When to reach for this:

• Sizing init payer transfers in Anchor programs
• Estimating user onboarding cost (how many accounts to create)
• Closing accounts to reclaim rent
• Budgeting protocol treasury for account creation subsidies

Working Example

use anchor_lang::prelude::*;
 
#[derive(Accounts)]
pub struct InitConfig<'info> {
    #[account(
        init,
        payer = payer,
        space = 8 + Config::INIT_SPACE,
    )]
    pub config: Account<'info, Config>,
    #[account(mut)]
    pub payer: Signer<'info>,
    pub system_program: Program<'info, System>,
}
 
#[account]
#[derive(InitSpace)]
pub struct Config {
    pub admin: Pubkey,
    pub fee_bps: u16,
}

import { createSolanaRpc } from "@solana/kit";
 
const rpc = createSolanaRpc("https://api.devnet.solana.com");
const space = 8 + 32 + 2; // discriminator + fields
const minBalance = await rpc.getMinimumBalanceForRentExemption(BigInt(space)).send();
console.log("Rent-exempt minimum:", minBalance, "lamports");

What this demonstrates:

• init transfers at least the rent-exempt minimum from payer to new account
• Space calculation must include Anchor's 8-byte discriminator
• RPC returns the exact lamport amount for any byte size

Deep Dive

How It Works

• Rent is a function of data size and a network-wide lamports-per-byte-year rate
• Rent-exempt means holding ~2 years of rent upfront - account is never charged ongoing rent
• The lamports sit in the account's balance - reclaimable on close
• System Program enforces minimum balance on allocation

Typical Sizes

Exact values change with cluster parameters - always query RPC.

Gotchas

• Undersized space in Anchor - init fails or truncates data. Fix: use InitSpace derive or manual calculation with max string/vec lengths.
• Forgetting discriminator in space - off by 8 bytes. Fix: always add 8 for Anchor accounts.
• Assuming rent is a recurring charge - rent-exempt accounts pay once. Fix: fund to minimum at creation; no ongoing billing.
• Not reclaiming rent on close - user funds locked forever. Fix: implement close constraint.
• Hardcoding rent values - cluster params can change. Fix: query getMinimumBalanceForRentExemption in clients.

Alternatives

FAQs

Related

• Creating & Closing Accounts - reclaim rent
• Account Anatomy - lamports field
• Data Accounts & Layout - sizing layouts

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.