Change outputs

When you spend a coin worth more than the payment, the rest returns to you as a change output. Learn why change exists and why it can matter for privacy.

Why change exists

UTXOs are spent whole. If you own a 0.5 BTC UTXO and want to pay 0.2 BTC, your wallet creates two outputs:

• 0.2 BTC to the person you are paying.
• 0.2999 BTC back to a new address in your own wallet: the change.
• The missing 0.0001 BTC is the fee.

Don't forget the change

If you built a transaction by hand and left out the change output, the entire difference would go to the miner as a fee. Wallets handle change automatically, which is one reason to use good wallet software.

Can others tell which output is change?

Not for certain. The blockchain doesn't label it. Analysts use clues (round amounts, address types, script types) to guess. MyBitcoinExplorer never asserts which output is change, because a guess can be wrong. See Chain analysis heuristics.

Change and privacy

If an observer can guess which output is your change, they can follow your remaining money to your next payment. Clues they use:

• A round payment amount and an odd-looking change amount.
• Change sent to the same address type as the inputs.
• Change sent back to an address already used as an input.

Good wallets randomise or avoid these patterns. See Address reuse and privacy.

Avoiding change altogether

Some wallets search for a combination of coins that matches the payment plus fee almost exactly, so no change output is needed. That saves space and removes a privacy clue.