Transaction Fees

A transaction fee is a fee that is required in order to process a transaction on the Aleo network. Below, we describe the way in which Deploy and Execute transactions are priced. At the time of writing, puzzle solutions are free.

Aleo Credits Denomination Table

Denomination	Size of Transaction	Value	Example
microcredit	Byte	1	Smallest denomination
millicredit	Kilobyte (KB)	1000 microcredits	Most transactions average between 3 and 10 millicredits
credit	Megabyte (MB)	1000 millicredits	Largest denomination

Types of Transaction Fees

Deployment Base Fee

This is what you pay for deploying a program to the Aleo network. Deployment fees consist of the following parts:

• Storage Cost: Determined by the amount of raw bytes of your program. The cost is calculated as size_in_bytes × DEPLOYMENT_FEE_MULTIPLIER, where DEPLOYMENT_FEE_MULTIPLIER is currently 1 millicredit per byte.
• Namespace Cost: The smaller your program name, the more you pay. There is no namespace cost if your program name is 10 characters or longer.
• Synthesis Cost: To process your program into a circuit for zero knowledge proofs. The cost is based on the number of variables and constraints: (num_variables + num_constraints).
• Constructor Cost: The operations performed in the program's constructor are also accounted for in the deployment fee. The constructor currently has a 100× fee multiplier compared to the finalize cost.

Execution Base Fee

This is what you pay for executing program functions on the Aleo network.

• Execution Cost: Determined by the amount of raw bytes of your execution transaction. For transactions smaller than 5,000 bytes (5 KB), the cost is linear: size_in_bytes. For larger transactions, a quadratic penalty applies: size_in_bytes² / 5000. This quadratic formula discourages excessively large transactions.
• Finalize Cost: Based on the operations performed in your function's finalize scope. Each operation has a specific cost in microcredits, including:
  • Mapping operations (get, set, remove, contains)
  • Hash operations (different costs for different hash functions)
  • Cryptographic operations (ECDSA verification, etc.)
  • Arithmetic and logical operations
  • These per-operation costs vary depending on the consensus fee version.
• Proof Verification: There is minimal execution cost for proof verification, as verifying zero knowledge proofs is computationally cheap. The expected proof size is included in the cost calculation.

Priority Fee

Priority fees are optional fees that allow users to bid for higher transaction priority in the mempool. With the approval of ARC-0005, priority fees are now supported and effectively created a fee market for transaction ordering.

The network maintains a priority queue for transactions that include a nonzero priority fee. This priority queue is processed before the standard transaction queue when sending transactions to the BFT consensus layer.

notes on current design

1. Priority fees for transactions already in the mempool cannot be updated.
2. There is no protection against starvation: if the priority pool stays full enough, transmissions from the standard queue will not be sent to the BFT.
3. Batch building is not atomic w.r.t. the memory pool.

Estimating Fees

The fee determination logic is defined in a file called cost.rs. If you want to quickly estimate fees using a website, provable.tools has some limited support. Or you can also use Leo CLI to estimate the fees for your transaction. Example as below:

First, generate a example program using leo example.

leo example lottery
cd lottery

Then use leo deploy to estimate the deployment fees for your transaction.

leo deploy --network testnet --endpoint https://api.explorer.provable.com/v1

Or use leo execute to estimate the execution fees for your transaction.

leo execute main 1u32 2u32 --endpoint https://api.explorer.provable.com/v1 --network testnet 

This method works without needing to fund the private key and will look something like below:
Deployment

📊 Deployment Summary for helloworld.aleo
──────────────────────────────────────────────
  Total Variables:      16,995
  Total Constraints:    12,927
  Max Variables:        2,097,152
  Max Constraints:      2,097,152

💰 Cost Breakdown (credits)
  Transaction Storage:  0.879000
  Program Synthesis:    0.029922
  Namespace:            1.000000
  Constructor:          0.002000
  Priority Fee:         0.000000
  Total Fee:            1.910922
──────────────────────────────────────────────

Execution

📊 Execution Summary for helloworld.aleo
──────────────────────────────────────────────
💰 Cost Breakdown (credits)
  Transaction Storage:  0.001321
  On‑chain Execution:   0.000000
  Priority Fee:         0.000000
  Total Fee:            0.001321
──────────────────────────────────────────────

Fees Visibility

On Aleo, each transaction contains a dedicated fee transition. The fee may be provided by the sender or by a sponsor, and it can be paid either publicly or privately. The fee amounts themselves (base and optional priority) are always public, what differs is the on‑ledger visibility of the payer.

Public fee payment

Paid from a public account. The payer’s address and the total fee (base + priority) are visible on the ledger. The payer publicly signs the fee transition, and the amount is deducted from their public balance during finalize.

important

For public fees, the payer’s public account must have sufficient balance at verification time.

Private fee payment

Paid from a private credits.record. The payer’s address is not revealed, a private change record is produced. Only the fee amounts and a public link to the target transaction are disclosed. To keep a private transaction fully private, the fee should be paid privately.

Fee Sponsorship

A separate party can provide the fee via an independent fee authorization that is combined with the sender’s execution authorization. Sponsors may pay publicly or privately. For maximum sender privacy a private‑sponsored fee is preferred, public sponsorship links the sponsor’s address to the target transaction ID.

note

Every fee transition carries a public field binding it to a specific deployment or execution ID, ensuring the fee is verifiably associated with the intended transaction.

special case

All transactions require a base fee, except the transaction that contains only a single call to credits.aleo/split or credits.aleo/upgrade may omit the base fee (a priority fee may still be included). Any multi‑transition transaction requires a fee.