How to read Bitcoin transaction outputs and change
Find your receiving address and read that output’s amount. Other outputs may be change or payments to other recipients.
Why a payment can have several outputs
Bitcoin spends previous transaction outputs. An unspent transaction output is often called a UTXO. A new transaction can pay a recipient and send the remainder to another address controlled by the sending wallet. That remainder is change. Transactions can also pay several recipients at once.
What is a UTXO? A worked payment exampleFollow the amounts, not a guessed label
In a made-up example, a wallet spends 0.0100 BTC, pays 0.0030 BTC to a recipient and uses 0.0001 BTC for the network fee. It has 0.0069 BTC left to return as change. The arithmetic explains that example; it does not prove which output is change in an unfamiliar transaction.
How to check your own payment
Match the complete receiving address to the original payment request. Read that output’s bitcoin amount instead of assuming the transaction’s total is what you received. If you are the sender, use your wallet’s own payment details to identify its change. UTXOHub lists the outputs without assigning an owner to each one.
Why did I receive less bitcoin?An address is not a whole wallet
A wallet can control many receiving and change addresses. A balance on one address may therefore be only part of what the wallet controls. Fresh receiving addresses can make payments harder to link, but Bitcoin’s transaction history remains public. Do not publish your wallet’s extended public key to explain a single payment.
What an extended public key revealsCan I reuse a Bitcoin address?References
- Bitcoin Developer Guide, “Transactions”.
- Bitcoin.org, “Protect your privacy”.