Overview
A pruned node is a full node that has validated the entire blockchain from the genesis block to the current tip but has deleted older block data to conserve disk space. Despite discarding historical blocks, a pruned node maintains the complete UTXO set, meaning it can fully validate all new transactions and blocks. Pruning makes running a full node feasible on devices with limited storage.
How Pruning Works
Full Archival Node: Pruned Node:
┌─────────────────────┐ ┌─────────────────────┐
│ Block 1 [kept] │ │ Block 1 [deleted] │
│ Block 2 [kept] │ │ Block 2 [deleted] │
│ Block 3 [kept] │ │ Block 3 [deleted] │
│ ... │ │ ... │
│ Block 800000 [kept] │ │ Block 800000 [del.] │
│ Block 800001 [kept] │ │ Block 800001 [kept] │
│ Block 800002 [kept] │ │ Block 800002 [kept] │
├─────────────────────┤ ├─────────────────────┤
│ UTXO Set [kept] │ │ UTXO Set [kept] │
├─────────────────────┤ ├─────────────────────┤
│ Disk: ~600+ GB │ │ Disk: ~10-20 GB │
└─────────────────────┘ └─────────────────────┘
Both validate ALL consensus rules identically
Configuration
In Bitcoin Core, pruning is enabled by setting the prune parameter in bitcoin.conf:
prune=550— Keep only the most recent 550 MB of block data (the minimum)prune=10000— Keep 10 GB of recent blocks
During initial sync, the pruned node downloads and validates every block, updating the UTXO set as it goes, then deletes blocks older than the configured threshold.
What Pruned Nodes Can and Cannot Do
Can do:
- Validate all new blocks and transactions
- Enforce all consensus rules
- Relay new transactions and blocks
- Use the built-in wallet
Cannot do:
- Serve historical blocks to peers performing initial block download
- Rescan old blocks for wallet transactions (e.g., importing an old key)
- Provide block data for block explorers or analytics
Trade-offs
Pruning dramatically reduces storage requirements — from over 600 GB for a full archival node down to as little as 10 GB. The trade-off is that the pruned node cannot help new nodes bootstrap by serving old blocks, which means the network relies on archival nodes for that function. However, pruned nodes still contribute to network security by validating and relaying new data.
Common Misconception
A pruned node is not a "light node" or SPV client. It has validated every single block in Bitcoin's history and maintains the full current UTXO set. The only thing it lacks is the ability to reproduce old block data on request. Its security guarantees are identical to an archival full node.