PERFORMANCE · SEO GLOSSARY
First Contentful Paint (FCP)
A performance metric measuring the time from page navigation start until the browser renders the first piece of content — text, image, or SVG — on screen. FCP is not a Core Web Vital but is a useful early-load diagnostic.
Definition
First Contentful Paint (FCP) measures the time from when the browser starts loading a page to when any piece of content — text, an image, a background image, or an SVG — is first rendered to the screen. It's the first signal that something is loading. FCP differs from the Core Web Vitals in several ways: (1) FCP is not a ranking signal — it's a diagnostic metric, not one of the three Core Web Vitals (LCP, INP, CLS); (2) FCP measures when the first pixel appears, not when the primary content is usable — LCP is the more relevant perception-of-speed metric; (3) FCP can be gamed by showing a spinner or background colour quickly while the actual content loads slowly, which is why Google replaced it with LCP as the primary load metric. Thresholds (from Lighthouse): Good ≤1.8s, Needs Improvement 1.8–3.0s, Poor >3.0s. FCP and LCP are correlated but distinct: a page with Good FCP but Poor LCP suggests the first content appears quickly but the main content element (hero image, H1) takes much longer to render.
Why it matters for SEO
FCP is useful as a diagnostic because it isolates whether the page is starting to render quickly. If FCP is Poor (>3s), the problem is in the critical rendering path — likely render-blocking CSS or JavaScript, slow TTFB, or font loading blocking text rendering. If FCP is Good but LCP is Poor, the rendering path is healthy but the specific LCP element (typically a large hero image) is slow to load — the fix targets the image specifically (preload, priority, format, CDN) rather than the overall critical path. In Lighthouse reports, FCP appears alongside LCP, TBT (Total Blocking Time), CLS, and Speed Index — it's useful context but shouldn't distract from the Core Web Vitals that are actual ranking signals.
How DeepSEOAnalysis checks this
FCP is measured in Lighthouse lab runs during the crawl, providing a per-page snapshot of critical-rendering-path performance. The audit surfaces FCP alongside LCP in performance reports to help diagnose whether load issues are in the overall rendering path (poor FCP) or specific to the LCP element (good FCP, poor LCP). Real-world FCP field data is not available in CrUX — the CrUX API provides LCP, INP, and CLS for field data; FCP field data is not included in the Core Web Vitals report. For ranking purposes, focus on improving LCP, INP, and CLS — the Core Web Vitals that are ranking signals.
Useful tools and resources
GLOSSARY
Related terms
performance
Core Web Vitals
Three Google metrics — LCP, INP, and CLS — that measure real-user loading, interactivity, and visual stability.
Read definition →performance
Time to First Byte (TTFB)
The time between a browser sending an HTTP request and receiving the first byte of the server's response — a measure of server response speed that influences crawl rate and LCP.
Read definition →performance
Page Speed
The time it takes for a page to load and become usable — measured by multiple metrics including TTFB, FCP, and Core Web Vitals.
Read definition →performance
INP (Interaction to Next Paint)
The Core Web Vital that measures a page's responsiveness to user interactions — replacing FID in March 2024 as a Google ranking signal. Good INP is under 200ms.
Read definition →See how your site scores on First Contentful Paint (FCP).
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