--- title: Constants Reference description: Centralized reference for all Solana runtime constants including accounts, transactions, instructions, programs, fees, compute units, PDAs, and CPIs. url: /docs/core/constants-reference type: reference prerequisites: [] related: - /docs/core/accounts/account-structure - /docs/core/transactions/transaction-structure - /docs/core/fees/compute-budget - /docs/core/programs/syscall-reference --- This page is a single reference for all runtime constants mentioned across the core concept pages. Each constant links to its source definition in the [agave](https://github.com/anza-xyz/agave/tree/v3.1.8) validator client or [solana-sdk](https://github.com/anza-xyz/solana-sdk). ## Accounts | Constant | Value | Description | Source | | ----------------------------------------- | ------------------------- | ---------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------- | | `MAX_ACCOUNT_DATA_LEN` | 10 MiB (10,485,760 bytes) | Maximum account data size | [`MAX_ACCOUNT_DATA_LEN`](https://github.com/anza-xyz/agave/blob/v3.1.8/transaction-context/src/lib.rs#L34) | | `MAX_ACCOUNT_DATA_GROWTH_PER_TRANSACTION` | 20 MiB (20,971,520 bytes) | Max new account data allocated per transaction | [`MAX_ACCOUNT_DATA_GROWTH_PER_TRANSACTION`](https://github.com/anza-xyz/agave/blob/v3.1.8/transaction-context/src/lib.rs#L38) | | `MAX_PERMITTED_DATA_INCREASE` | 10,240 bytes (10 KiB) | Max realloc increase per CPI | [`MAX_PERMITTED_DATA_INCREASE`](https://github.com/anza-xyz/solana-sdk/blob/clock%40v2.2.3/account-info/src/lib.rs#L17) | | `TRANSACTION_ACCOUNT_BASE_SIZE` | 64 bytes | Per-account overhead counted toward loaded data size | [`TRANSACTION_ACCOUNT_BASE_SIZE`](https://github.com/anza-xyz/agave/blob/v3.1.8/svm/src/account_loader.rs#L45) | ## Transactions | Constant | Value | Description | Source | | ------------------------------ | ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------ | | `PACKET_DATA_SIZE` | 1,232 bytes | Maximum transaction size (IPv6 MTU minus headers) | [`PACKET_DATA_SIZE`](https://github.com/anza-xyz/solana-sdk/blob/clock%40v2.2.3/packet/src/lib.rs#L32) | | `MAX_ACCOUNTS_PER_TRANSACTION` | 256 | Hard ceiling from `u8` index encoding. The enforced runtime limit is [64](https://github.com/anza-xyz/agave/blob/v3.1.8/runtime/src/bank.rs#L2942) (128 when [`increase_tx_account_lock_limit`](https://github.com/anza-xyz/agave/blob/v3.1.8/feature-set/src/lib.rs#L1652) is activated, currently inactive). | [`MAX_ACCOUNTS_PER_TRANSACTION`](https://github.com/anza-xyz/agave/blob/v3.1.8/transaction-context/src/lib.rs#L29) | | `MAX_PROCESSING_AGE` | 150 slots | Blockhash expiry window | [`MAX_PROCESSING_AGE`](https://github.com/anza-xyz/solana-sdk/blob/clock%40v2.2.3/clock/src/lib.rs#L133) | | `MAX_RECENT_BLOCKHASHES` | 300 entries | BlockhashQueue size | [`MAX_RECENT_BLOCKHASHES`](https://github.com/anza-xyz/solana-sdk/blob/clock%40v2.2.3/clock/src/lib.rs#L127) | | `MAX_SIGNATURES_PER_PACKET` | 12 | Maximum signatures per transaction packet | [`MAX_SIGNATURES_PER_PACKET`](https://github.com/anza-xyz/agave/blob/v3.1.8/transaction-view/src/signature_frame.rs#L18) | ## Instructions | Constant | Value | Description | Source | | ------------------------------ | --------------------- | --------------------------------------------- | ------------------------------------------------------------------------------------------------------------------ | | `MAX_INSTRUCTION_TRACE_LENGTH` | 64 | Maximum total instructions (top-level + CPIs) | [`MAX_INSTRUCTION_TRACE_LENGTH`](https://github.com/anza-xyz/agave/blob/v3.1.8/transaction-context/src/lib.rs#L41) | | `MAX_INSTRUCTION_DATA_LEN` | 10,240 bytes (10 KiB) | Maximum instruction data per instruction | [`MAX_INSTRUCTION_DATA_LEN`](https://github.com/anza-xyz/agave/blob/v3.1.8/transaction-context/src/lib.rs#L33) | ## Programs | Constant | Value | Description | Source | | ------------------------------------- | -------------------------------------------------------------------- | --------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------- | | `MAX_LOADED_ACCOUNTS_DATA_SIZE_BYTES` | 64 MiB (67,108,864 bytes) | Default loaded accounts data size limit | [`MAX_LOADED_ACCOUNTS_DATA_SIZE_BYTES`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L53) | | `PROGRAM_OWNERS` | BPF Loader Upgradeable, BPF Loader, BPF Loader Deprecated, Loader V4 | Valid program owner loaders | [`PROGRAM_OWNERS`](https://github.com/anza-xyz/solana-sdk/blob/clock%40v2.2.3/account/src/lib.rs#L802) | | `STACK_FRAME_SIZE` | 4,096 bytes | SBF stack frame size | [`STACK_FRAME_SIZE`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L37) | | `MAX_CALL_DEPTH` | 64 | Maximum SBF-to-SBF call depth | [`MAX_CALL_DEPTH`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L34) | | `MAX_LOADED_ENTRY_COUNT` | 512 | Maximum cached programs | [`MAX_LOADED_ENTRY_COUNT`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/loaded_programs.rs#L31) | | `DELAY_VISIBILITY_SLOT_OFFSET` | 1 slot | Program deployment visibility delay | [`DELAY_VISIBILITY_SLOT_OFFSET`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/loaded_programs.rs#L32) | ## Fees & Compute | Constant | Value | Description | Source | | ------------------------------------------- | ----------------------- | ---------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------- | | `DEFAULT_INSTRUCTION_COMPUTE_UNIT_LIMIT` | 200,000 CUs | Default CU limit per instruction | [`DEFAULT_INSTRUCTION_COMPUTE_UNIT_LIMIT`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L44) | | `MAX_BUILTIN_ALLOCATION_COMPUTE_UNIT_LIMIT` | 3,000 CUs | Default CU limit per builtin instruction | [`MAX_BUILTIN_ALLOCATION_COMPUTE_UNIT_LIMIT`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L47) | | `MAX_COMPUTE_UNIT_LIMIT` | 1,400,000 CUs | Maximum CU limit per transaction | [`MAX_COMPUTE_UNIT_LIMIT`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L39) | | `lamports_per_signature` | 5,000 lamports | Default base fee per signature | [`FeeStructure::default()`](https://github.com/anza-xyz/solana-sdk/blob/clock%40v2.2.3/fee-structure/src/lib.rs#L210) | | `MICRO_LAMPORTS_PER_LAMPORT` | 1,000,000 | Micro-lamports per lamport conversion | [`MICRO_LAMPORTS_PER_LAMPORT`](https://github.com/anza-xyz/agave/blob/v3.1.8/compute-budget/src/compute_budget_limits.rs#L17) | | `MAX_HEAP_FRAME_BYTES` | 262,144 bytes (256 KiB) | Maximum BPF heap size | [`MAX_HEAP_FRAME_BYTES`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L48) | | `DEFAULT_HEAP_COST` | 8 CUs per 32 KiB page | Cost to allocate heap pages | [`DEFAULT_HEAP_COST`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L43) | | `HEAP_LENGTH` | 32,768 bytes (32 KiB) | Default BPF heap size | [`HEAP_LENGTH`](https://github.com/anza-xyz/solana-sdk/blob/clock%40v2.2.3/program-entrypoint/src/lib.rs#L42) | | `WRITE_LOCK_UNITS` | 300 CUs | Compute cost per write-locked account | [`WRITE_LOCK_UNITS`](https://github.com/anza-xyz/agave/blob/v3.1.8/cost-model/src/block_cost_limits.rs#L20) | | `SIGNATURE_COST` | 720 CUs | Compute cost per Ed25519 signature | [`SIGNATURE_COST`](https://github.com/anza-xyz/agave/blob/v3.1.8/cost-model/src/block_cost_limits.rs#L10) | | `SECP256K1_VERIFY_COST` | 6,690 CUs | Compute cost per secp256k1 signature | [`SECP256K1_VERIFY_COST`](https://github.com/anza-xyz/agave/blob/v3.1.8/cost-model/src/block_cost_limits.rs#L12) | ## PDA | Constant | Value | Description | Source | | ----------------------------- | ------------- | ------------------------------------------ | ---------------------------------------------------------------------------------------------------------------------------- | | `MAX_SEEDS` | 16 | Maximum number of seeds per PDA derivation | [`MAX_SEEDS`](https://github.com/anza-xyz/solana-sdk/blob/clock%40v2.2.3/pubkey/src/lib.rs#L47) | | `MAX_SEED_LEN` | 32 bytes | Maximum length of a single seed | [`MAX_SEED_LEN`](https://github.com/anza-xyz/solana-sdk/blob/clock%40v2.2.3/pubkey/src/lib.rs#L45) | | Bump seed range | 255 down to 1 | Range tried for canonical bump | [`find_program_address`](https://github.com/anza-xyz/solana-sdk/blob/clock%40v2.2.3/pubkey/src/lib.rs#L800) | | `create_program_address` cost | 1,500 CUs | CU cost per PDA derivation syscall | [`create_program_address_units`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L200) | ## CPI | Constant | Value | Description | Source | | ----------------------------- | ------------------------------ | ------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `MAX_INSTRUCTION_STACK_DEPTH` | 5 (9 with SIMD-0268) | Maximum call stack depth | [`MAX_INSTRUCTION_STACK_DEPTH`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L8), [`MAX_INSTRUCTION_STACK_DEPTH_SIMD_0268`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L10) | | `DEFAULT_INVOCATION_COST` | 1,000 CUs (946 with SIMD-0339) | CPI invocation cost | [`DEFAULT_INVOCATION_COST`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L21), [`INVOKE_UNITS_COST_SIMD_0339`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L23) | | `MAX_SIGNERS` | 16 | Maximum PDA signers per CPI | [`MAX_SIGNERS`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/cpi.rs#L62) | | `MAX_CPI_ACCOUNT_INFOS` | 128 (255 with SIMD-0339) | Maximum account infos passed to a CPI | [`MAX_CPI_ACCOUNT_INFOS`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/cpi.rs#L122), [`MAX_CPI_ACCOUNT_INFOS_SIMD_0339`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/cpi.rs#L124) | | `MAX_RETURN_DATA` | 1,024 bytes | Maximum return data from a CPI | [`MAX_RETURN_DATA`](https://github.com/anza-xyz/solana-sdk/blob/clock%40v2.2.3/cpi/src/lib.rs#L329) | | `cpi_bytes_per_unit` | 250 bytes per CU | CPI serialization cost rate | [`cpi_bytes_per_unit`](https://github.com/anza-xyz/agave/blob/v3.1.8/program-runtime/src/execution_budget.rs#L205) |