What is bitcoin dust?

Bitcoin dust is a very small amount of bitcoin leftover (i.e. unspent) after a transaction has taken place. The amount is so small that the bitcoin fee to send it to someone is larger than the amount of the bitcoin itself.

Remember there is technically no such thing as a bitcoin and you will never see a single bitcoin in the blockchain, only Satoshis are recorded there. A single bitcoin is made up of 100 million Satoshis - see the diagram below - it shows how small a Satoshi is :

Beginners are often confused that only 21 million bitcoin will ever exist but now that you know that each bitcoin is broken up into 100 million separate units the total amount of Satoshis that will be minted is 21 million x 100 million = 2,100,000,000,000,000 units of trade - for the mathematicians amongst you that is 2 quadrillion 100 billion (or 2 million billion) or if you are a computer it is 111011101011111000001011010000001110100000000000000 in binary!

Many wallets agree that bitcoin dust is any amount of bitcoin less than 546 sats (0.00000546 bitcoin), however the bicoin dust limit actually changes with the popularity of the network and the current price of bitcoin.

You can actually receive bitcoin dust without doing anything - this is called a dusting attack (or just dusting). In a dusting attack, dust is usually sent to a large number of public addresses, in order to try to track payments and connect them to an individual.

If you do notice very small amount of bitcoin appearing in your wallet it is possibly someone trying to deanonymize (or unmask) you - remember they do not have control over your wallet or funds - but if the dust gets spent in a future transaction they can track your movements on tools like the blockchain explorers and if this includes bitcoin from an exchange where you have done KYC (Know Your Customer) - then they know who is performing the transaction!