Gas and transaction fees
Why every blockchain transaction has a fee, how fees are set and why they change with network load.
Every blockchain transaction carries a fee. The fee pays the miners or validators who include the transaction in a block, and it protects the network from spam.
Why fees change
Blocks have limited space. When many people want to transact at the same time, they compete for that space by offering higher fees. Fees therefore rise when the network is busy and fall when it is quiet.
Bitcoin
Bitcoin fees depend on the size of a transaction in bytes (more inputs = larger transaction) and on demand. Wallets usually suggest a fee rate in satoshis per virtual byte (sat/vB).
Ethereum and EVM networks
On Ethereum, each operation consumes a certain amount of gas. The fee is the gas used multiplied by the gas price. A simple transfer uses little gas; a complex smart contract call uses more. Part of the fee (the base fee) is burned, and the rest (the priority fee) goes to the validator.
TRON
TRON uses resources called bandwidth and energy. Accounts can get them by staking TRX or pay for them in TRX. Transfers of USDT (TRC-20) use energy, so they cost TRX.
Practical tips
- Always keep a little of the network's native coin to pay fees (ETH for Ethereum, TRX for TRON).
- A transaction with a very low fee may wait a long time.
- The network fee is separate from any fee a service charges. For example, XFasil does not charge a deposit fee, but your wallet still pays the network fee.
University materials are for education only and are not investment, legal or tax advice.