What is dust?

An amount of crypto too small to move, because the network fee to send it would exceed its value.

Dust accumulates from partial fills, rewards, and airdrops. Some exchanges provide a conversion tool that sweeps dust balances into a single token. The threshold is not fixed: what counts as dust rises and falls with the fee market, so the same output can be spendable on a quiet day and stranded on a busy one.

The point people miss is that dust is a property of the fee, not of the amount. A balance of a few cents is dust on a congested chain and perfectly movable on a cheap one, which is why the same holding behaves differently depending on which network it sits on.

How it works

On a utxo chain such as Bitcoin, your balance is a set of separate outputs rather than one number. Spending an output adds bytes to the transaction, and those bytes cost money at the current rate per virtual byte. If an output is worth less than the fee to include it, spending it loses money.

Bitcoin Core encodes this directly. It refuses to relay an output as too small when spending it would cost more than a third of its value at the default relay fee rate, which for a standard pay-to-public-key-hash output works out to 546 satoshis (source: Bitcoin Core). Segregated witness outputs are cheaper to spend, so the threshold for them is lower.

On account-based chains such as Ethereum there are no outputs, but the same economics apply to the balance itself: a token worth less than the gas required to transfer it cannot profitably be moved.

Exchanges handle it differently. Many run a conversion feature that sweeps small balances into the exchange's own token or a stablecoin at a stated rate, because the exchange holds the funds internally and does not pay a network fee to do it.

Example

Illustrative arithmetic. A Bitcoin input adds roughly 68 virtual bytes to a transaction when spent from a segregated witness address. At a fee rate of 20 satoshis per virtual byte, including that input costs about 1,360 satoshis. An output holding 900 satoshis therefore costs more to spend than it is worth, so it stays where it is until fee rates fall below about 13 satoshis per virtual byte.

Why it matters when you buy

Buying in many small transfers, or withdrawing repeatedly in small amounts, leaves you with a wallet full of outputs that are individually cheap to create and collectively expensive to spend. Consolidating when fees are low is the fix. Compare withdrawal charges before you split a purchase across venues at the fee comparison.

Related terms

utxo — why a balance is many pieces, network fee — the cost that defines the threshold, coin control — choosing which outputs to spend, dusting attack — dust sent to deanonymize you, sat vb — the fee rate unit involved, withdrawal fee — what exchanges charge to send.

Questions

Can I get rid of dust in my exchange account?

Many exchanges offer a small-balance conversion that exchanges dust for their own token or a stablecoin, usually with a stated conversion rate and limits on how often it can be used. Check the exchange's own help pages for its terms.

Does dust in my wallet cost me anything?

Holding it costs nothing. It only matters when you try to spend it, or when your wallet automatically selects it as an input and inflates the fee for an unrelated transaction.

Is a tiny incoming transfer always an attack?

No. Change from a payment, a rounding remainder, or a partial fill produces dust innocently. Treat unexpected tokens from unknown senders with suspicion, and ordinary change from your own spending as normal.