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The numbers every audit is measured against.
An audit is only worth something if the targets in it come from somewhere. These are the seven figures we work to, what each one actually measures, and which two of them are our own assumptions rather than published research.
Google and SOASTA measured what happens to mobile visitors as a page gets slower. Past three seconds, 53 percent of them abandon. It is the single most quoted figure in web performance and it is the one behind the calculator on our home page.
This is how long until the biggest thing on the screen appears. Google treats under 2.5 seconds as good and over 4 seconds as poor. We build to under 2.0 on a 4G connection, which leaves headroom for a bad day on the network.
A measure of how much the page jumps around while it loads. Anything that moves after you have started reading counts against it. This site targets 0.02, which is why every image and video in it carries explicit width and height attributes.
How quickly the page responds when somebody taps something. It replaced first input delay in 2024 and it is the metric most often failed by sites carrying a lot of third party script.
Advertised 4G speeds and what a buyer actually gets on a factory floor in Ludhiana are different numbers. We model at 6 Mbps. This is the one figure on this page that is a working assumption rather than a published benchmark, and it is deliberately conservative.
Google indexes the mobile version of a site rather than the desktop one. A site with no mobile layout is not being read the way its owner assumes, and content that only appears on desktop may as well not exist.
Everything needed to render the first screen, including fonts and the hero image. This is a budget rather than a standard, set so that the LCP target is achievable at 6 Mbps rather than merely hoped for.
Where each one comes from
- Google and SOASTA, 2017Three seconds, and half your mobile visitors are gone
- Google Core Web VitalsLargest contentful paint under 2.5 seconds
- Google Core Web VitalsCumulative layout shift under 0.1
- Google Core Web VitalsInteraction to next paint under 200 milliseconds
- Our working figureA realistic 4G throughput, not an advertised one
- GoogleMobile first indexing
- Our working figureAbove the fold transfer under 900 KB
Two of the seven are ours rather than anybody else's research, and they are labelled that way above. We would rather tell you which numbers are assumptions than present all seven as though they carried equal authority.