Library · Crypto, word by word · Inside Bitcoin
What is a change address?
A change address is where a Bitcoin wallet sends the leftover when the coins you spend are larger than the payment. Coins must be spent whole, so using a 0.5 BTC coin for a 0.2 BTC payment creates a second output returning about 0.3 BTC, minus the fee, to an address in your own wallet.
What it means for you
On a block explorer the change appears as a second output, which can look like money leaving your wallet when it has come back to you. If you build a transaction by hand and leave out the change output, the entire difference goes to the miner as a fee and cannot be recovered.
How it works
Bitcoin tracks coins as unspent transaction outputs (UTXOs), and an output must be spent in full. A transaction therefore lists inputs that cover the payment and creates outputs for the recipient and for the surplus going back to the spender: the change output. Whatever the inputs exceed the outputs by is claimed as the fee by the miner who includes the transaction. Wallets send change to a fresh address rather than an existing one, because reusing addresses makes it easier to link payments to the same owner.
An example
Say your wallet holds one coin of 100,000 sats and you pay 30,000 sats with a 1,000-sat fee. The transaction spends the whole 100,000-sat coin and creates two outputs: 30,000 sats to the recipient and 69,000 sats of change to a new address in your wallet.
Source: Bitcoin Developer Guide: Transactions · checked 4 October 2026
Related words
Educational content, not financial advice. Written by hand and checked against the source named above. Something wrong? Tell us and we reply within two business days.