Features / Core Web Vitals
Core Web Vitals test: score, metrics and fixes for any page
Paste a page address into the SEOSage desktop app for Mac or Windows and it tests the page on mobile and desktop. You get a score from 0 to 100, the Core Web Vitals and other main speed metrics, a picture of the page, plain fixes and a history for that address.
Jump to: The screen · What it checks · Examples · How it works · Questions
See a Core Web Vitals test in 20 seconds
Paste a page address and SEOSage tests it on mobile and desktop: a score from 0 to 100, the main speed metrics and plain fixes.
Read the video transcript
How fast is your page? Paste an address. SEOSage tests it on mobile and desktop, and gives a score from zero to one hundred. See every metric, and plain fixes for the biggest problems. Then test again. Start your fourteen-day free trial at seosage.co.
See the score, the metrics and the fixes
One screen shows the score, the Core Web Vitals result, the main metrics and the fixes for a page. This is how a desktop result looks.
Score 82 · Core Web Vitals Assessment: Failed
*INP is estimated from blocking time.
What a Core Web Vitals test shows
- Score from 0 to 100: Worked out from LCP, blocking time, CLS and FCP. 90 or more is Good, 50 to 89 is Needs work, and under 50 is Poor
- Core Web Vitals assessment: Passed or Failed. It passes when LCP (main content loads in 2.5 s or less), CLS (layout shift is 0.1 or less) and the INP estimate (blocking time is 200 ms or less) are all in the good range
- Metrics with a marker: LCP, INP, CLS, FCP, TTFB and page weight, each on a bar that shows good, needs work or poor
- Page preview: A picture of the page as it loaded. With SEOSage's own test it shows the whole page, top to bottom up to a limit, and you can scroll it
- How to fix: Plain-English fixes for the biggest problems, such as slow main content, scripts that block the page, content that shifts, slow server response and a heavy page
- Largest files: The biggest files the page loaded, with their sizes
- History for each address: The last 3 results for an address, with score, LCP, CLS and page weight. SEOSage keeps up to 30 for each address on your computer
What it measures, and what it does not
Desktop is measured on your computer and your own internet connection, without slowing it down on purpose. Mobile is an estimate: SEOSage loads the page at phone size, then works out the timings for a slow phone on Slow 4G from the weight of the page and the blocking time. INP is also an estimate, worked out from the blocking time.
A test is one load of one page, a lab test. It is not data from real visitors. If you add a Google PageSpeed key in Settings and choose it for tests, SEOSage asks Google instead. You then get Google's own score and metrics.
What the fixes look like
Examples of the plain-English fixes in the How to fix box. The numbers come from the page you test:
- Largest content loads slowly. The main content appears at 3.4s. Optimize the biggest image or text block, preload it, and use faster hosting or a CDN.
- JavaScript is blocking the page. The page stayed busy for 420ms during load. Split or defer large scripts and remove unused code.
- Content shifts while loading. Layout-shift score is 0.180 (6 images have no width/height set). Set width and height on images and reserve space for banners and embeds.
How it works in three steps
- Open Core Web Vitals.It is in the site menu, under Insights. The home page address is already filled in.
- Press Test.SEOSage tests each address on mobile and desktop. Add more addresses, one per line, up to 20.
- Read the result and fix.Switch between Mobile and Desktop, read How to fix, then test again to see the new score in the history.
Related: SEO crawler · competitor analysis · speed checks in a crawl.
Questions about this check
What does the Core Web Vitals page measure?
It loads a page in the app's own built-in browser and measures LCP (main content), CLS (layout shift), FCP (first content), TTFB (server response) and page weight. INP is estimated from the blocking time. It then gives a score from 0 to 100.
Is the mobile score exact?
No. Mobile is an estimate for a slow phone on Slow 4G, worked out from the page weight and the blocking time, so it is approximate. For Google's own mobile score, use a Google PageSpeed key.
Does it show real-visitor data?
No. The built-in test is a lab test of one page load, not data from real visitors.
Do I need a Google key?
No. Without one, SEOSage uses its built-in test, which runs on your computer. A key is optional and is kept encrypted. If you use Google, the page address is sent to Google to be tested.
How many pages can I test at once?
Up to 20 addresses at a time, each on mobile and desktop. The page shows the last 3 results for an address, and SEOSage keeps up to 30.
Does it need a crawl?
No. It tests any address you paste, and it also works while a crawl is running.
More SEOSage features
Every check and tool in the app, each with its own page.
SEO crawler Crawl settings Page audit Change tracking Compare crawls Rank tracking Search Console report Google Analytics report Robots.txt and sitemap audit Backup and restore Local site audit Custom extraction Internal linking tool Orphan pages Link strength Canonical tag checker Title tag width checker URL structure checker Security headers check Keyword cannibalization Search Console quick wins Competitor analysis Weekly SEO to-do list Fix and re-check White-label reports Ask Claude All features
Try it on your own site
Download SEOSage for Mac or Windows. The 14-day trial needs a card to start and charges nothing for 14 days. Then $19 a month or $149 a year.