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Chrome User Experience Report

Changelog

The CrUX dataset on BigQuery is updated on the second Tuesday of every month. Each release is numbered according to the year and calendar month of the data collection period, for example 201912 corresponds to the UX data collected during December 2019 and would be released on the second Tuesday of January 2020 after the data collection period has ended.

In the list below, we've curated some release notes for each monthly dataset. Subscribe to our CrUX Announce mailing list or follow @ChromeUXReport on Twitter for release announcements.

202101

Announcement
Publication date
February 10, 2021
Notable stats

202012

Announcement
Publication date
January 12, 2021
Notable stats

202011

Announcement
Publication date
December 8, 2020
What's new
As of December 3, PageSpeed Insights (web and API) is sourcing its field data from the CrUX API, bringing the tools closer in alignment.
We rolled out a small accuracy improvement to metrics' 75th percentiles in the CrUX API.
The API results were frozen for a few days at the end of November and the issue has since been fixed.
Notable stats

202010

Announcement
Publication date
November 10, 2020
What's new
A CLS issue in Chrome 86 may cause regressions in CLS scores:
Sites with absolutely positioned content with negative offsets outside the viewport will see large regressions in their Cumulative Layout Shift scores until the fix rolls out to stable.
Notable stats

202009

Announcement
Publication date
October 13, 2020
What's new
No major changes in this release!
Notable stats

202008

Announcement
Publication date
September 9, 2020
What's new
There was a bump in origin coverage this month (+3.3%) due in part to a data pipeline change. Previously, for a user experience record to be included in the dataset, it must have included FP, DCL, and OL measurements. Now, the only required metric is FCP. This change helps to ensure that we're capturing more meaningful user experiences.
Notable stats

202007

Announcement
Publication date
August 11, 2020
What's new
No major changes in this release!
Notable stats

202006

Announcement
Publication date
July 14, 2020
What's new
User experiences served from Google's AMP cache are now attributed to the publisher's origin in CrUX. Effects will vary depending on the amount of AMP cache traffic relative to the rest of the website, but most origins see less than a 5 percentage point change in Core Web Vitals performance, with most effects being positive.
Notable stats

202005

Announcement
Publication date
June 9, 2020
What's new
There were two LCP updates, which should have a minimal effect on most origins:
"Largest Contentful Paint measurement should stop at the first input or scroll on the page. In Chrome 83, inputs and scrolls in subframes were correctly accounted for."
"When comparing sizes of images for Largest Contentful Paint, the visual size of a background image was previously computed as the size of its Layout Object. This is not correct in all cases; for example in the case of CSS styles like :first-letter. This issue was fixed in Chrome 83."
There was one FID update, which may result in some sites observing faster FID experiences:
"In Chrome 83, a bug was fixed in the implementation of First Input Delay (FID). Prior to M83, First input delay values less than 1ms were not reported to the Chrome User Experience Report (CrUX)."
Notable stats

202004

Announcement
Publication date
May 12, 2020
What's new
There was a small improvement to the way LCP is measured in M81. This may manifest itself in your CrUX data as a slight shift in slower LCP or in rare cases too few LCP samples to include for your origin.
Introducing Web Vitals! CrUX is committed to providing you with all of your Core Web Vital metrics to give you an accurate picture of how real users experience the web.
Do you query data on a per-country basis? Give the new experimental.country table a try! It's optimized to make querying across country and monthly datasets super easy.
Notable stats
  • 6,389,861 origins

202003

Announcement
Publication date
April 14, 2020
What's new
CLS histogram start/end values changed from INT64 to NUMERIC type and divided by 100. This change aligns CLS with the fractional layout shift values provided by the Layout Instability API.
Notable stats
  • 5,937,298 origins

202002

Publication date
March 10, 2020
Notable stats
  • 6,366,736 origins

202001

Publication date
February 11, 2020
What's new
Experimental metric on notification permission acceptance rates
Notable stats
  • 5,976,293 origins

201912

  • 5,532,155 origins

201911

  • 5,821,306 origins
  • the FID metric was moved from experimental.first_input_delay to first_input.delay
  • the CLS metric was moved from experimental.cumulative_layout_shift to layout_instability.cumulative_layout_shift

201910

  • 5,752,729 origins

201909

  • 6,008,004 origins
  • the LCP metric was launched as largest_contentful_paint
  • CLS was updated to take move distance into account
    • coverage may be lower while Chrome users upgrade to the latest version of the Layout Instability API

201908

  • 6,011,463 origins
  • FID coverage has returned to normal
  • the average percent of fast experiences for most metrics dropped by about 2%

201907

  • 5,612,504 origins
  • there was an incremental update to Chrome's FID implementation, which included pointer events on mobile
    • coverage will be lower while Chrome users update to the latest version

201906

  • 5,624,797 origins
  • the TTFB metric was added to the list of experimental metrics as experimental.time_to_first_byte

201905

  • 5,884,155 origins
  • the CLS metric was added to the list of experimental metrics as experimental.cumulative_layout_shift

201904

  • 5,744,982
  • there was an incremental update to Chrome's FID implementation
    • coverage will be lower while Chrome users update to the latest version

201903

  • 5,703,255 origins
  • there was an incremental update to Chrome's FID implementation
    • coverage will be lower while Chrome users update to the latest version

201902

  • 5,464,560 origins

201901

  • 5,351,287 origins

201812

  • 4,654,112 origins

201811

  • 4,697,003 origins

201810

  • 4,374,729 origins

201809

  • 4,375,805 origins

201808

  • 4,386,422 origins
  • histogram bins have been normalized to consistent widths (more info)

201807

  • 4,202,945 origins

201806

  • 4,134,123 origins
  • the FID metric was added to the list of experimental metrics as experimental.first_input_delay (learn more)

201805

  • 4,162,633 origins

201804

  • 3,970,181 origins

201803

  • 3,589,954 origins

201802

  • 3,237,524 origins

201801

201712

  • 1,939,945 origins

201711

201710