Definition
An equal-output CoinJoin is the most common privacy-preserving collaborative transaction structure on Bitcoin. Participants agree on a uniform output value, for example 0.1 BTC, and each contributes inputs worth at least that amount. The resulting transaction pays out many identical-value outputs, so an outside observer cannot tell which output belongs to which input. This indistinguishability is what creates a meaningful anonymity set and improves the fungibility of the coins.
Why equal denominations are required
If outputs had arbitrary values, a chain analyst could often match an input's amount to an output's amount and undo the mix. By forcing every mixed output to the same denomination, the transaction produces genuine ambiguity: with N participants and N equal outputs, there are many plausible input-to-output mappings. Cascading several rounds multiplies this ambiguity, so coins gain privacy that compounds over successive mixes.
The change-output trade-off
Because few real balances are an exact multiple of the chosen denomination, most participants also receive a non-equal change output. Change outputs trivially reveal themselves as the odd amounts, so disciplined users isolate or avoid spending change alongside mixed coins. Newer protocols allow variable input amounts while still producing standardized mixed outputs, reducing change leakage. Understanding this trade-off is essential to spending mixed funds without re-linking them.
See also post-mix spending and CoinJoin coordinator.
In Simple Terms
An equal-output CoinJoin is the most common privacy-preserving collaborative transaction structure on Bitcoin. Participants agree on a uniform output value, for example 0.1 BTC, and…