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What is slow costing you?

ShaneWebGuy Tools · Google grades your speed. This works out whether it is worth fixing.

Your Core Web Vitals

Get these free from PageSpeed Insights or Search Console, and enter them exactly as shown there. Or measure the page you are on right now.

In seconds, as PageSpeed shows it. Good is 2.5 or less.
In milliseconds. Good is 200 or less.
A score, not a unit. Good is 0.1 or less.
LCP · loading
INP · responsiveness
CLS · visual stability
ENTER YOUR NUMBERS

What that is plausibly worth

Google can measure your speed. It cannot know your business. These three numbers are the part only you have.

Sessions a month, from your analytics.
Share of visits that become a sale or enquiry.
A sale, or what an enquiry is worth to you on average.
Your assumption, not a fact. Default is eBay's measured figure.
Where that assumption comes from, and why it is only an estimate

The default of 5% per second is drawn from the one same-site figure in Deloitte and Google's Milliseconds Make Millions (2020): eBay phased in speed work across a year and measured a 0.5% rise in Add to Cart per 0.1 second saved.

That same study's better known headline, 8.4% more conversions per 0.1 second for retail, is a correlation across 37 different brands, not a before and after on one site. The report says so itself, and warns the results "may not fully reflect an individual site's product offering, design, or seasonality". Applied to a typical one and a half second gap it implies more than doubling your conversions, which is not credible. That is why this tool defaults to the smaller, same-site number instead.

Two more limits worth knowing. The study measured mobile only, and explicitly could not establish the same relationship on desktop. And it measured 0.1 second changes, so stretching it across a large gap is already beyond what was tested. Treat the figure below as the size of the prize under an assumption you control, not a forecast.

You will also see nothing here for INP or CLS. There is no published conversion elasticity for either, so putting a number on them would be invention.

What causes this on a WordPress site

The usual culprits behind your worst metric, most common first.

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