---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/glossary/i420#article
headline: Planar Y'UV 4:2:0 (I420)
description: "*Video standard*. The data format that encodes video into three independent memory blocks to save storage space."
url: https://www.twilio.com/docs/glossary/i420
inLanguage: en
dateModified: 2026-09-15T15:39:36.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# Planar Y'UV 4:2:0 (I420)

*Video standard*. The data format that encodes video into three independent memory blocks to save storage space.
Also known as Planar Y'UV 4:2:0, this format stores video data in memory blocks called [*planes*][planes] of luminance (`Y`) set per pixel and chrominance (`U`, `V`) set per four-pixel block.

## Planes (`Y'UV`)

The [Y'UV][] notation defines how each frame stores color. One plane stores brightness data ([luma][] (`Y`)) and two planes of color data ([chroma][] (`U`, `V`)). These planes must be presented in this order. The U and V planes get sub-sampled both horizontally and vertically by a factor of two compared to the Y plane. Each sample in this format uses eight bits.

## Subsampling (`420`)

Each [two by two block of pixels][subsample] registers four brightness levels but the block shares one blue-difference (`U`) and one red-difference (`V`) color sample.

[planes]: https://developer.mozilla.org/en-US/docs/Web/API/VideoFrame/format

[subsample]: https://wiki.multimedia.cx/index.php/YCbCr_4:2:0

[luma]: https://en.wikipedia.org/wiki/Luma_\(video\)

[chroma]: https://en.wikipedia.org/wiki/Chrominance

[Y'UV]: https://en.wikipedia.org/wiki/Y%E2%80%B2UV