> ## Documentation Index
> Fetch the complete documentation index at: https://manuals.cobo.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Transaction fee models
> Learn how major blockchain networks calculate transaction fees and how to configure the right parameters for your transfers.
In blockchain networks, transaction fees determine not only whether a transfer is confirmed but also how quickly it is processed. Since each network adopts a different calculation model, understanding these rules is essential for making informed configuration choices.
## EVM chains
### EIP-1559 model
Some EVM chains support [EIP-1559](https://eips.ethereum.org/EIPS/eip-1559). Currently supported chains include:
* Ethereum Mainnet
* Sepolia Testnet
* Scroll Mainnet
* Base
* BNB Smart Chain
* Polygon
* Sonic
* Berachain
In the EIP-1559 model, the estimated transaction fee is calculated as: (base fee + priority fee) \* gas limit
| Parameter | Description |
| ------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Base fee | The maximum amount you are willing to pay per gas unit to execute the transaction on-chain. |
| Priority fee | The maximum additional fee per gas unit paid to miners/validators to prioritize your transaction. |
| Gas limit | The maximum number of gas units you are willing to spend to execute the transaction or run the Ethereum Virtual Machine (EVM). Different operations consume different amounts of gas units. |
For both Legacy and EIP-1559 fee models, an additional fee is charged when submitting transaction calldata to L1 (Layer 1).
You can customize the following parameters:
* Max fee: The maximum total fee for the transaction.
* Max priority fee: The maximum additional fee per gas unit paid to miners/validators to prioritize your transaction.
* Gas limit
### Legacy model
All EVM chains support the Legacy model.
In the Legacy model, the estimated transaction fee is calculated as: gas price \* gas limit
| Parameter | Description |
| --------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Gas price | The gas price in gwei, representing the amount of ETH paid to validators per gas unit to process the transaction. |
| Gas limit | The maximum number of gas units you are willing to spend to execute the transaction or run the Ethereum Virtual Machine (EVM). Different operations consume different amounts of gas units. |
For both Legacy and EIP-1559 fee models, an additional fee is charged when submitting transaction calldata to L1 (Layer 1).
You can customize the following parameters:
* Gas price
* Gas limit
## UTXO-based chains
Currently supported chains include:
* Bitcoin
* Cardano
* Nervos CKB
* Handshake
On UTXO-based chains, the estimated transaction fee is calculated as: fee rate \* transaction size
| Parameter | Description |
| ---------------- | ------------------------------------------------------------------------------------------------------ |
| Fee rate | The fee per byte of data, indicating how many satoshis are paid per vByte (abbreviated as sats/vByte). |
| Transaction size | The on-chain space occupied by the transaction, which affects the total fee in UTXO models. |
You can customize the following parameters:
* Fee rate
## Solana
On Solana, you can use the native model or choose the Legacy model. In the native model, the estimated transaction fee is calculated as: base fee + (CU price \* CU limit)
| Parameter | Description |
| --------- | --------------------------------------------------------------------------------------------------------------------------- |
| base fee | A fixed fee charged per signature (by default, 5,000 Lamports per signature). |
| CU price | The price per Compute Unit (CU), used to increase transaction priority. Denominated in Lamports. |
| CU limit | The maximum number of CUs the transaction is allowed to consume. A higher value increases priority but also increases cost. |
You can customize the following parameters:
* CU price
* CU limit
## Filecoin
On Filecoin, you can use the native model or choose the Legacy model. In the native model, the estimated transaction fee is calculated as: min(gas fee cap, base fee + gas premium) \* gas limit
| Parameter | Description |
| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Gas fee cap | The maximum price you are willing to pay per unit of gas. |
| Base fee | The minimum fee required for block inclusion, which adjusts dynamically with network congestion and is burned after payment, thereby reducing the total FIL supply. |
| Gas premium | A user-specified miner tip to increase transaction priority. |
| Gas limit | The maximum amount of gas the transaction is allowed to consume. |
You can customize the following parameters:
* Gas fee cap
* Gas premium
* Gas limit
## Chains using the fixed model
The following chains adopt a fixed fee model:
* TRON
* Algorand
* Polkadot
* Internet Computer and its ICRC assets (ckBTC, ckETH, ckUSDC, ckUSDT, DKP, GLDGOV, ICS, NICP, OC, OGY)
* Stellar
* Ripple
* Tezos
* Sui
* Near
The fixed fee model charges a fixed fee for each transaction.
If you need to estimate transaction fees using the WaaS 2.0 API, please refer to [Estimate transaction fees](https://www.cobo.com/developers/v2/guides/transactions/estimate-fees).