Dust is an output worth less than it costs to spend. Learn the dust limit, when to consolidate small UTXOs to save fees, and the privacy trade-off.
What is dust?
Each input you spend adds roughly 58 to 148 vB to a transaction. If an output is worth less than the fee needed to spend it, it's uneconomical: that's dust.
Nodes also have a dust limit in their relay policy: by default Bitcoin Core won't relay transactions creating outputs below a few hundred sats (the exact threshold depends on the output type).
Consolidation
If you have many small UTXOs, spending them later, when fees may be high, will be expensive. Consolidation means spending many of them together into one output, ideally when fees are low.
The privacy cost
Spending UTXOs together shows the world they likely belong to the same owner. See Chain analysis heuristics. Consolidate coins that are already linked, and keep separate the ones you want separate, using Coin control.
A consolidation plan
- Wait for a quiet mempool: check the mempool page for low fee rates.
- Select only coins you don't mind linking together, using Coin control.
- Send them to a fresh address in your own wallet at a low fee rate.
- Be patient: low-fee consolidations can take hours or days.
How much can you save?
Consolidating 20 small native SegWit inputs at 1 sat/vB costs roughly 1,400 sats. Spending those same 20 inputs later at 50 sat/vB would cost roughly 68,000 sats.
Key takeaways
- Dust is an output worth less than the cost of spending it.
- Consolidating small UTXOs during low fees saves money later.
- Merging UTXOs links them, which affects privacy.
Common questions
When should I consolidate?
When the mempool is quiet and low fee rates confirm quickly, for UTXOs you don't mind linking.
What should I do with unknown dust?
Many people freeze it in their wallet and never spend it.
What is the dust limit in sats?
It depends on the output type: roughly 546 sats for legacy, 294 for native SegWit and 330 for Taproot outputs in Bitcoin Core's default policy.
Should I spend dust I didn't expect?
Usually not. Unknown tiny deposits may be dust attacks; freezing them is safest.