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block weight

Also: block weight limit, 4,000,000 WU limit

A block's size as consensus counts it, in weight units: every non-witness byte weighs 4 WU and every witness byte 1 WU, and a block may weigh at most 4,000,000 WU.

Because a non-witness byte weighs 4 WU, a block of non-witness bytes alone reaches the limit at 1,000,000 bytes: the "1 MB block" of before SegWit. Witness bytes weigh a quarter as much, so a block carrying mostly witness data, like an inscription, can hold nearly 4 MB. Space Blocks' image of 1,047,584 bytes, more than a pre-SegWit block could hold, sits in one transaction of 1,054,167 WU, 26.4 % of the limit; the largest inscriptions, close to 4 MB, fill nearly a whole block.

Used by: spaceblocks.art, block.space

Used on #

Sources #

  1. block.space docs: data types · block.space/docs/datatypes
  2. The spaceblocks.art site: README, index.html, whole-blocks/ and tools/build.py · spaceblocks.art

Updated 2026-10-20 · This page as Markdown

blockspace.wiki is written by Blockspace Holdings from its published documents and records and the live data of its own Bitcoin node and indexers. Every page cites its sources; corrections go in the errata.