A concrete example
A 0.10 BTC input can fund a payment, a change output and a fee.
In context
If you control a 0.10 BTC output and send 0.03 BTC with a 0.0001 BTC fee, you can create a 0.03 BTC recipient output and a 0.0699 BTC change output. Inputs minus outputs equal the fee. These are illustrative amounts, not a live fee estimate.
The related mechanism, visually
- 01Inputs: 110,000 sat
- 02Consume both outputs
- 03Payment 80,000 + change 28,000
- 04Difference: fee 2,000
Read these as connected concepts, not necessarily consecutive steps.
Read the explanation
A Bitcoin wallet balance is a sum of spendable outputs. A transaction consumes complete outputs and creates new ones. It cannot partially retain an input. Change therefore becomes a new output, usually to an address controlled by the same wallet. The fee is the difference between total inputs and total outputs; it is not a separate output addressed to a miner.
Put the mechanism into context
Use fictional inputs of 70,000 and 40,000 satoshis. Pay 80,000 satoshis and allocate 2,000 to fees. Create a table with inputs on one side and payment, change and fee on the other. Every satoshi must be accounted for.
Apply it in the workshop →What this mechanism does not guarantee
Coin selection affects transaction size and privacy. Combining several inputs can reveal that they are likely controlled together. Receiving many tiny outputs can make a future payment expensive. An address is not a permanent account balance, and a wallet may display many addresses while managing one recovery backup.
Explore the full explanation
Bitcoin UTXOs explained
Bitcoin records unspent transaction outputs, or UTXOs.