blockspace.wiki

4 MB transaction relay

Research: relaying transactions up to 4 MB, the whole block weight. Stock Bitcoin Core stops at 100 kvB, so it needs a patched node; none relays them here today.

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

What it is #

The Labs site describes it as "relaying transactions up to 4 MB, the whole block weight". A block may weigh up to 4,000,000 weight units. Relay policy is stricter: "Stock Bitcoin Core treats a transaction over 400,000 weight units (100 kvB) as non-standard and does not relay it, so this needs a patched node." A transaction above that size is not a standard transaction, so ordinary nodes will not pass it on, even though a block may contain it.

Where it stands #

It is a research project, not a running service. The Labs node runs stock Bitcoin Core (/Satoshi:28.2.0/, as of block 972,308, 2026-10-20 11:17:25 UTC), which keeps the 400,000 WU limit. The card says it plainly: "No node here relays 4 MB transactions today." It stays marked Research until such a node runs.

Background #

block.space's data-types reference names the limit MAX_STANDARD_TX_WEIGHT. It says a larger transaction, such as the 3.94 MB Taproot Wizards inscription it cites, needs direct-to-miner submission. The relay policy page sets this limit beside the node's other policy settings, and weight units and vbytes explains how a transaction is weighed.

The standard transaction size is one of the relay levers in blockspace expansion policy. The policy observatory proposes to count mined transactions over 100 kvB, which reach miners off the standard relay path.

Sources #

  1. The blockspacelabs.com page (index.html) · blockspacelabs.com
  2. block.space docs: data types · block.space/docs/datatypes
  3. Blockspace Holdings records

Live figures: relay as of block 972,308, 2026-10-20 11:17:25 UTC. Refreshed hourly.

Updated 2026-10-20 · This page as Markdown