Denominations
The fixed-denomination pool uses a small set of fixed note sizes. Equal-sized notes are what let one deposit hide among the others, so amounts are bucketed and public rather than arbitrary.
The set
| Lamports | SOL |
|---|---|
5,000 | 0.000005 |
50,000,000 | 0.05 |
100,000,000 | 0.1 |
1,000,000,000 | 1 |
Why fixed sizes
If deposits could be any amount, the amount itself would fingerprint a withdrawal: a 0.37 SOL deposit and a 0.37 SOL withdrawal are obviously the same note. Fixing the sizes means every note of a given denomination looks identical, so a withdrawal hides among all deposits of that size. The crowd you hide in is the set of equal notes, which is why this matters for the anonymity set.
Choosing a denomination
Larger, more commonly used denominations generally sit in a bigger anonymity set than rare ones. When privacy matters more than convenience, prefer a denomination that many others also use. The deposit and withdraw flows in the fixed-denomination pool use these sizes directly.