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First Contentful Paint Calculator

Calculate first contentful paint from its network and rendering components.

About First Contentful Paint Calculator

First contentful paint marks when the user first sees anything. Render-blocking resources are usually the largest controllable component, and eliminating them moves FCP earlier directly. FCP is what users perceive as the page starting to load, which is why it drives bounce rate even though LCP drives ranking.

Formula

First Contentful Paint

FCP = TTFB + critical CSS time + render-blocking resource time

render blocking
Stylesheets and synchronous scripts that must load before first paint

Worked example

With the default values below, First Contentful Paint Calculator returns First Contentful Paint of 890. Change any input above and every figure here is recalculated in your browser.

Inputs used

DNS lookupminimum 0 ms
40 ms
TCP and TLS handshakeminimum 0 ms
120 ms
Server response timeminimum 0 ms
250 ms
Critical CSS parse and renderminimum 0 ms
180 ms
Render-blocking resource timeminimum 0 ms
300 ms

Results

First Contentful Paint
890 ms
First Contentful Paint
0.890 s
Time to First Byte
410 ms
Rating
Good
Saving From Removing Blocking Resources
300 ms

Step by step

  1. 1Values used
  2. 2First Contentful Paint
  3. 3First Contentful Paint= 890 ms
  4. 4First Contentful Paint= 0.890 s
  5. 5Time to First Byte= 410 ms
  6. 6Rating= Good
  7. 7Saving From Removing Blocking Resources= 300 ms

Assumptions and limits

  • The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is First Contentful Paint calculated?

FCP = TTFB + critical CSS time + render-blocking resource time First contentful paint marks when the user first sees anything. Render-blocking resources are usually the largest controllable component, and eliminating them moves FCP earlier directly.

Why does First Contentful Paint matter?

FCP is what users perceive as the page starting to load, which is why it drives bounce rate even though LCP drives ranking.

What values do I need to enter?

This calculator takes 5 inputs: DNS lookup, TCP and TLS handshake, Server response time, Critical CSS parse and render, Render-blocking resource time. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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