Gas and Fees

When sending a message to the network, a specific amount of Venom tokens must be attached. This is used to compensate validators for their work, cover the costs of storing the message on the network, and any remaining balance is returned as change.

This system serves multiple purposes:

1. To incentivize validators to ensure the network runs smoothly, perform transaction calculations, and store contract data on their nodes.

2. To restrict the ability to send spam to the network and prevent attempts by malicious parties to slow it down.

There are several important characteristics of commissions:

The cost per unit of gas on the network is fixed and is outlined in the global configuration, which can only be modified by the consensus of validators.

Gas cost in the network

Currently, one gas unit in the network costs 100 nanoVENOM

The network also charges a commission for data storage for the entire duration of their existence in the network

The commission is always paid from the contract balance, as external messages cannot be value-bearing messages.

The user decides how much VENOM to attach as payment fees from their contract account for the call. The attached value is the upper limit for the cost of executing the call chain. Typically, the DApp automatically suggests a recommended value for the user.

Fee Calculation

As we know from the article Messages and Transactions , there are several phases of transaction execution. Each phase is associated with its own type of fee.

Inbound external message fee: the only fee that is not related to the transaction execution phases described. It is charged when a transaction is initiated by an external message, as a fee for sending the message (forward message fee).

Fees in the context of execution phases:

Storage: related to the namesake fee (Storage fee) and charged for storing the contract and associated data.

Credit: the only phase that does not involve the charging of any fee.

Compute: charges a fee (Gas fee) for calculations performed in the called account (contract).

Action: each outgoing message from the contract, both external and internal, must be paid a fee (Action fee) as a fee for sending the message.

Bounce: in case of an error, an exception will be created and an internal outgoing message will be taken for which a fee will be charged as a fee for sending the message.

As a result, the formula for forming a transaction fee is as follows:

transaction_fee = inbound_external_message_fee
                + storage_fees                    // Storage
                + gas_fees                        // Compute
                + total_action_fees               // Action
                + outbound_internal_messages_fee  // Action + Bounce

Inbound external message fee

When an inbound external message is imported for transaction execution, a fee is calculated and paid to the current validators using the standard forwarding fee formula. This fee is referred to as the action fee.

Forward message fee

This formula represents the total fee for forwarding a message, which is calculated by adding the lump_price to the price of forwarding the message's bits and cells. The price of forwarding the message's bits and cells is calculated by multiplying the price per bit and the number of bits in the message, and the price per cell and the number of cells in the message. The final result is then rounded up to the nearest integer number.

$$msg\_fwd\_fee = lump\_price + \left\lceil\ bit\_price \cdot bits + cell\_price \cdot cells \right\rceil$$

The bits and cells values are derived from the tree of cells representation of the message, with the root cell not being counted.

The lump_price, bit_price, and cell_price values are found in the global configuration parameters p24 and p25, and can only be changed by a vote of validators.

Storage fees

As mentioned earlier, in Venom, every transaction has a storage phase that incurs a storage fee charged to the account balance. This fee is calculated using the following formula and is charged for the time between transactions:

The storage fees are calculated by first multiplying the number of bits by the global bit price and the number of cells by the global cell price. This result is then multiplied by the period value.

Finally, the result is rounded up to the nearest integer.

$$storage\_fees = \left\lceil (bits * global\_bit\_price + cells * global\_cell\_price) * period \right\rceil$$

Where:

bits and cells: represent the number of bits and cells in the Account structure, which is represented as a tree of cells (including code and data).

global_bit_price: a global configuration parameter (p18 for both the masterchain and workchains), which is the price for storing one bit.

global_cell_price: another global configuration parameter (p18 for both the masterchain and workchains), which is the price for storing one cell.

period: the number of seconds since the previous storage fee payment.

Gas fees

For most primitives, gas is calculated using the following formula:

$$Pb := 10 + b$$

Where b is the instruction length in bits

Gas fees are only applicable if the TVM compute phase is initialized for a transaction. If the compute phase is not initialized, these fees may be skipped.

Action fees

Action fees are used to cover the cost of performing send message actions. These fees are comprised of all fees for external outbound messages, as well as the first fraction of internal outbound message fees. The calculation of Action fees is as follows:

$$total\_action\_fees = total\_out\_ext\_msg\_fwd\_fee + total\_int\_msg\_mine\_fee$$

• total_out_ext_msg_fwd_fee: the sum of implicit forward fees for all generated outbound external messages.
• total_int_msg_mine_fee: the sum of 'mine' parts of message forward fees for outbound internal messages.

The action fee might be absent if no actions are performed during the transaction.

Outbound messages

The outbound_internal_messages_fee is determined by adding up the fees for each outbound internal message generated as a result of transaction execution.

$outbound\_internal\_messages\_fee = \sum_{i=1}^{n} (out\_int\_msg\_i.fwd\_fee + out\_int\_msg\_i.ihr\_fee)$

where n is the number of outbound internal messages.