Largest Contentful Paint Test
Measure LCP against the 2.5-second threshold, with the TTFB and render metrics that usually explain it.
- 100% free
- No sign-up
- No limits
- Instant results
What is Largest Contentful Paint Test?
Largest Contentful Paint is the moment the biggest thing on screen finishes rendering — usually a hero image, a video poster or a large block of text.
It is the closest single number to "when did this page become useful", which is why Google made it a Core Web Vital. Good is 2.5 seconds or under, poor is above 4. The number on its own rarely tells you what to change, which is why this tool shows Time to First Byte next to it: if TTFB is already 2 seconds then no amount of image optimisation will fix your LCP, because the browser had not received anything to render.
How to use Largest Contentful Paint Test
- 1
Test the page, not the site
LCP is per URL. A landing page with a hero video behaves nothing like a text article.
- 2
Look at TTFB first
If TTFB is slow, that is your LCP problem and it lives on the server or the CDN, not in the markup.
- 3
Then find the LCP element
It is almost always the largest above-the-fold image. Make sure it is not lazy-loaded, and preload it if it arrives via CSS or JavaScript.
- 4
Check mobile separately
Mobile is throttled to a slower connection and CPU, and it is the number Google weights.
Everything this tool
does for you
- LCP against the 2.5s and 4s thresholds
- TTFB shown alongside for diagnosis
- FCP and TBT for the fuller picture
- Mobile and desktop
- Free, no signup, no daily limit
Related free tools
Frequently asked questions
This tool fixed one thing.
Now fix the whole site.
Our scanner runs 240+ checks across 10 audit areas, ranks every issue by the score points it costs, and hands you the code to paste.
Run a free audit- LCP on mobile and desktop
- TTFB shown alongside — the most common cause
- Google’s 2.5s / 4s thresholds applied
- Supporting metrics for diagnosis
- Free, no account, no daily limit