- MrKeyword reads Google's Chrome UX Report (CrUX) History API for your whole site, once a week, for mobile and desktop separately.
- Each weekly point is the 75th percentile of LCP, INP and CLS for real Chrome visitors over the 28 days ending that week.
- Each metric shows its latest value, Google's rating (good, needs improvement or poor) and whether it is better or worse than eight weeks earlier, on a chart against Google's “good” limit.
- The data is measured by Google, never estimated. Sites without enough Chrome traffic have no CrUX data, and MrKeyword says so.
- It runs for every website on every plan, including Free. You can refresh on demand at most once an hour.
What Core Web Vitals monitoring is
Core Web Vitals are Google's three measures of page experience: Largest Contentful Paint (LCP) for loading, Interaction to Next Paint (INP) for how quickly the page responds to a tap or click, and Cumulative Layout Shift (CLS) for how much the layout jumps around. Google measures them on real visits in Chrome and publishes the results in the Chrome UX Report.
Monitoring means watching those numbers over time, not testing once. A single speed test tells you how one page loaded in a lab on one run. A weekly series of field data tells you whether the experience your real visitors get is improving, holding or slipping, and roughly when it changed, which is what you need after a redesign, a new plugin or a hosting move.
How MrKeyword tracks Core Web Vitals over time
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Find your site's origin
MrKeyword takes the address of the connected website, such as
https://example.com, and asks for data for the whole origin, which covers every page on it. -
Read the CrUX history, every week
It calls Google's CrUX History API once for phones and once for desktops. Google adds a new weekly point each Monday, and MrKeyword refreshes each website once a week. If Google's answer fails, it tries again after a day.
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Keep the 75th percentile for each week
For every week Google returns, MrKeyword stores the 75th percentile of LCP, INP and CLS. Google returns 25 weekly points by default, about six months of history. A week where Google has no data for a metric stays empty instead of being filled in.
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Rate it and compare it
The latest value of each metric gets Google's rating, and is compared with the value eight weeks earlier: better, worse or steady. The chart draws Google's “good” limit as a pale line, so you can see at a glance which side of it you are on.
Google's Core Web Vitals thresholds, at the 75th percentile
| Metric | Measures | Good | Needs improvement | Poor |
|---|---|---|---|---|
| LCP | Loading: when the largest content appears | 2.5 s or less | Over 2.5 s, up to 4 s | Over 4 s |
| INP | Responsiveness to taps, clicks and keys | 200 ms or less | Over 200 ms, up to 500 ms | Over 500 ms |
| CLS | Visual stability: unexpected layout shifts | 0.1 or less | Over 0.1, up to 0.25 | Over 0.25 |
Google recommends judging each metric at the 75th percentile of page loads, separately for mobile and desktop, and treats a page as passing when all three are good. Our guide to Core Web Vitals thresholds explains each one in more detail.
Where it appears in MrKeyword
In Site Audit, the Core Web Vitals over time card sits next to the Site speed card. The two answer different questions:
| Card | Data | Answers |
|---|---|---|
| Site speed | PageSpeed Insights, a snapshot | How does the site measure right now? |
| Core Web Vitals over time | CrUX History API, refreshed weekly | Is the real-visitor experience getting better or worse, and since when? |
The mobile and desktop switch on the Site speed card also switches the history card. Owners, admins and members can press Refresh to fetch the history now; it can be used once an hour per website, since Google only publishes new data weekly.
Small sites may have no data. Google only publishes Chrome UX Report data for origins that are publicly discoverable and have enough real Chrome visitors; its methodology explains the eligibility rules. When Google has no data for your site, the card says “Not enough real visitors in the Chrome UX Report yet” and stays empty. MrKeyword does not estimate the missing numbers, and the history appears once Google has it.
See your Core Web Vitals history freeConnect your website and the weekly LCP, INP and CLS history is on the Free plan too.
Start freeHow to read the trend
Each weekly point covers the 28 days ending that week, so consecutive points overlap by three weeks. That smooths out noise, but it also means a fix shows up gradually: expect a change to take about four weeks to be fully reflected.
- Worse than eight weeks ago, and now past the “good” line. Look at what shipped in that window: a theme or plugin update, new scripts, larger images, a hosting change.
- Mobile poor, desktop good. Common, because phones are slower and often on weaker connections. Fix for mobile first.
- Better than eight weeks ago. A fix is reaching real visitors. Keep watching until four new weeks have passed, when the old data has rolled out of the window.
- A gap in one metric. Google had too little data for that metric that week. It is not a zero.
Tiny movements are labelled steady rather than better or worse: under 50 milliseconds for LCP, under 5 milliseconds for INP and under 0.005 for CLS. That keeps rounding noise in Google's percentiles from looking like a change.
Google uses Core Web Vitals as part of its page experience signals; its Search Central page on Core Web Vitals describes how they relate to ranking and recommends achieving good values.
What MrKeyword does not do
- It does not show history for individual pages. The history is for the whole origin, all pages together.
- It does not measure visitors on Safari, Firefox or other browsers. The Chrome UX Report only covers eligible Chrome users.
- It does not estimate or model Core Web Vitals when Google has no data for your site.
- It does not send alerts when a metric gets worse. You see the change on the card.
- It does not fix your site. It shows where you stand and when it changed; the site audit helps find the causes.
Core Web Vitals history in each plan
The history is not metered. It is fetched for every connected website on every plan; the plan sets how many websites you can connect.
| Plan | Price | Websites tracked |
|---|---|---|
| Free | $0 | 1 |
| Starter | $10/month | 1 |
| Growth | $19/month | 3 |
| Agency | $49/month | 10 |
See pricing for every limit.
Questions and answers
Core Web Vitals questions
Where does MrKeyword get Core Web Vitals history?
From Google's Chrome UX Report History API. It returns the weekly 75th percentile of LCP, INP and CLS for real Chrome visitors to your whole site, separately for mobile and desktop. MrKeyword refreshes it once a week.
What are the good thresholds for LCP, INP and CLS?
Google rates LCP good at 2.5 seconds or less and poor above 4 seconds, INP good at 200 milliseconds or less and poor above 500, and CLS good at 0.1 or less and poor above 0.25, each at the 75th percentile.
Why does my site show no Core Web Vitals data?
Google only publishes Chrome UX Report data for sites with enough real Chrome visitors. Small or new sites often have none. MrKeyword shows a notice instead of estimating, and the history appears once Google has it.
How far back does the history go?
MrKeyword stores the weekly points Google returns by default, 25 weeks or about six months, and compares the latest week with eight weeks earlier.
How is this different from a PageSpeed Insights test?
A PageSpeed test is a snapshot of how the site scores now. The history card shows real-visitor results week by week, so you can see when something got better or worse.
Can I refresh the data whenever I want?
You can refresh once an hour per website. Google publishes a new weekly point on Mondays, so more frequent refreshes would return the same numbers.
Sources
- Web Vitals — web.dev, on LCP, INP and CLS and the 75th percentile
- Defining the Core Web Vitals metrics thresholds — web.dev, on the good and poor boundaries
- CrUX History API — Chrome for Developers, on weekly collection periods and Monday updates
- CrUX methodology — Chrome for Developers, on which sites are eligible for data
- Understanding Core Web Vitals and Google search results — Google Search Central
