Sub-1 sat/vB relay

Status on blockspacelabs.com: Live, the first card in the Live group.

What it is #

Blockspace Labs describes it in one line: "Our node relays and keeps transactions paying less than 1 sat/vB, the default floor of Bitcoin Core." This is sub-1 sat/vB relay. The node runs stock Bitcoin Core, not a patched build, with its fee floor (minrelaytxfee) set to 0. So a transaction that pays a fee rate below 1 sat/vB still enters the node's mempool and is passed on to its peers.

What the card shows #

The card shows the node's version, its fee floor, the mempool's size and the part of it paying below 1 sat/vB. A transaction counts as sub-1 when its base fee in sats is less than its vsize. In the reading of 2026-10-20 09:07:08 UTC, at block 972,298, the mempool held 38,991 transactions (23.7 vMB), and 38,265 of them (23.6 vMB) paid below 1 sat/vB.

The wiki's own reading of the node's policy, as of block 972,308, 2026-10-20 11:17:25 UTC:

• node: /Satoshi:28.2.0/;
• fee floor: 0 sat/vB;
• incremental relay fee: 1 sat/vB;
• full-RBF: on; maximum mempool: 300 MB.

How the figures are read #

Every figure on blockspacelabs.com "is read from our own node and indexers", once an hour, and nothing is loaded from elsewhere. For this card the job asks the node for its mempool and network information. A source that fails keeps its last reading with its own "as of". The card links to the mempool explorer at https://explore.block.space.

Related research #

Two Research cards build on this one: the sub-1 sat/vB share, a series of the share hour by hour, and low-fee propagation, which asks which of these transactions get mined. Relay policy puts the floor beside the node's other policy settings.

Related #

• blockspacelabs.com
• Relay policy
• Fee rate
• sub-1 sat/vB relay
• fee floor
• The sub-1 sat/vB share
• Low-fee propagation

Sources #

1. The blockspacelabs.com page (index.html) · blockspacelabs.com
2. Blockspace Labs facts (data/facts.json) · blockspacelabs.com
3. Blockspace Holdings records