Fees & Gas

This section describes how fees related to transaction execution are calculated and deducted in Tycho.

General Fee Deduction Scheme

In Tycho, there are several types of fees. Fees are deducted at the moment of transaction execution and depend on the execution context and network configuration parameters.

Main types of fees:

• account storage fee since the last payment

• fee for importing an external incoming message

• fee for VM computations, depending on consumed gas

• fee for creating outgoing messages

The cost of operations in the masterchain and in workchains may differ.

Network fee information is stored onchain as part of the global configuration.

Storage Fee

storage fee is the fee for account storage. It is charged every time a transaction is executed on this account.

The fee is calculated based on the time interval since the last payment and is proportional to the size of the stored state. If tariffs have changed over time, the calculation is done per tariff segment and summed.

storage_fee = ceil(((bit_price * bits) + (cell_price * cells)) * delta_seconds / 2^16)

Storage cost is regulated by values from ConfigParam 18. This parameter is stored onchain in the global configuration and contains a Hashmap 32 of type StoragePrices. Each entry sets storage prices starting from utime_since. Separate prices are set for the workchain and for the masterchain.

ConfigParam 18 = Hashmap(32, StoragePrices)

StoragePrices:
  utime_since: uint32
  bit_price_ps: uint64
  cell_price_ps: uint64
  mc_bit_price_ps: uint64
  mc_cell_price_ps: uint64

Import Fee

If a transaction is executed based on an external incoming message, the fee for importing this message is deducted from the account balance. This fee depends on the size of the incoming message.

The fee is calculated using the forwarding fee formula. The calculation considers the bits and cells of the message without the root cell and without the bits in the root cell.

The cost is taken from the onchain config ConfigParam 25.

import_fee = lump_price + ceil((bit_price * msg_bits + cell_price * msg_cells) / 2^16)

lump_price is the fixed part of the fee added regardless of the message size. It covers the base cost of forwarding and, in particular, includes payment for the data in the root cell of the message.

Example data from ConfigParam 25:

ConfigParam 25 = MsgForwardPrices

MsgForwardPrices:
  lump_price: 1_000
  bit_price: 2<<16
  cell_price: 100<<16
  ihr_price_factor: 0
  first_frac: 0x8000
  next_frac: 0x8000

---

Compute fee

compute fee is the fee for executing code in the VM.

It consists of a minimum charge for starting the VM and a charge for the gas actually consumed.

• the minimum charge for starting the VM is defined by the flat_gas_price parameter

• gas consumed above the flat_gas_limit threshold is charged at the gas_price rate

The fee formula is defined by the GasLimitsPrices parameters in the network configuration.

gas_fee = flat_gas_price + ceil(gas_price * max(0, gas_used - flat_gas_limit) / 2^16)

For the workchain, ConfigParam 21 is used. An example of data from ConfigParam 21.

ConfigParam 21 = GasLimitsPrices

GasLimitsPrices:
  flat_gas_limit: 100
  flat_gas_price: 10_000
  gas_price: 1_000<<16
  gas_limit: 1_000_000

Action fee

When a transaction is executed, a fee is charged for performing actions in the action phase. This fee is related to creating events and outgoing messages. The fee depends on the size of the generated outgoing messages.

The fee for a single outgoing message is calculated using the forwarding fee formula.

msg_fee = lump_price + ceil((bit_price * msg_bits + cell_price * msg_cells) / 2^16)

lump_price is the fixed part of the fee that is added regardless of the message size. It covers the base cost of processing an outgoing message and includes payment for the data in the message’s root cell.

The lump_price, bit_price, and cell_price parameters are taken from the on-chain config MsgForwardPrices. For the workchain, ConfigParam 25 is used.

An example of data from ConfigParam 25.

ConfigParam 25 = MsgForwardPrices

MsgForwardPrices:
  lump_price: 1_000
  bit_price: 2<<16
  cell_price: 100<<16
  ihr_price_factor: 0
  first_frac: 0x8000
  next_frac: 0x8000

Further Reading

For a deeper technical explanation, refer to the official TON documentation: https://docs.ton.org/foundations/fees