# The witness discount

A witness byte weighs a quarter of a base byte, so it costs a quarter as much at the same fee rate. The short version, with links to the full page.

URL: https://blockspace.wiki/basics/the-witness-discount/

The [witness discount](https://blockspace.wiki/glossary/witness-discount/) is the rule, from segwit, that a byte in a transaction's [witness](https://blockspace.wiki/glossary/witness/) counts 1 [weight unit](https://blockspace.wiki/glossary/weight-unit/) and every other byte counts 4. The full page, with the measurements and the theory, is [the witness discount](/concepts/witness-discount/). This is the short version.

## In one line

block.space's data-types reference: "witness bytes are real bytes on disk and on the wire, but count 1/4 toward the 4,000,000 WU consensus block limit." Because fees are priced in [vbytes](https://blockspace.wiki/glossary/vbytes/), a witness byte also costs a quarter as much as a base byte at the same [fee rate](https://blockspace.wiki/glossary/fee-rate/).

## What it changes

Where data goes depends on the price. The reference's channel comparison, per data byte at f sat/vB:

- a Taproot witness [envelope](https://blockspace.wiki/glossary/envelope/): 1 WU, f/4 sats;
- OP_RETURN: 4 WU, f sats.

That is why, in the reference's words, every high-volume protocol (ordinals, BRC-20, Alkanes WASM, Counterparty v11) "converged on" the witness envelope, while OP_RETURN keeps small structured messages such as runestones.

## How much each protocol takes

Bytes divided by vbytes shows how much of the discount a protocol takes. In the July 2026 measurement run on block.space it was 3.374 for inscriptions, 1.008 for stamps, 1.0000 for runestones and 1.0142 for Omni. [BTI](https://blockspace.wiki/glossary/bti/) keeps both raw bytes and vbytes on every row so this ratio stays visible.

## Two readings

The mechanism is a fact about weight. What it means is argued. Blockspace Value Theory proposes that the discount is "a price subsidy, not a capacity increase": witness bytes are downloaded, validated and stored like any others, so they use the same scarce resource at a quarter of the price. *BVT is a living document and an untested thesis.* BTI's books follow its measuring rule, raw bytes with no weight discounting, without taking a view on value.

Sources:

- block.space docs: data types · https://block.space/docs/datatypes
- block.space docs: measurements · https://block.space/docs/measurements
- block.space docs: Blockspace Value Theory · https://block.space/docs/bvt
- Blockspace Holdings records

Updated: 2026-10-20