Enter your store’s address, or a single product page. Google’s free mobile
test opens on its own site, and this page shows you how to read it: how fast it feels, what your
shoppers notice, and where to start.
The top section, about what your real users are experiencing, comes from real shoppers on
phones over the last 28 days. Where it’s there, it matters most. Smaller stores often don’t have
it yet.
Under “Diagnose performance issues”, the first circle, labelled Performance, is the lab
score out of 100: 90 and above is good, under 50 is poor.
Below the score, three numbers:
Largest Contentful Paint: how long until the main photo or headline
appears. Good is 2.5 seconds or less.Total Blocking Time: how long the page is too busy to answer a tap. Good
is 200 milliseconds or less.Cumulative Layout Shift: how much the page jumps. Good is 0.1 or
less.
Further down, the insights and diagnostics marked with an estimated saving are where Google
expects the biggest gains.
If it turns out slow
On my speed demo, a fictional static page I built with six common
problems (not a Shopify store), fixing them took Google’s mobile lab score from 68 to 96 on
22 September 2026.
I take on selected work through freelance platforms, such as Upwork, with the scope, price and deadline agreed in writing on the platform before I start. I’m not taking direct orders or bookings through this site.
What the check measures
Real-shopper data
When a store has enough visitors, Chrome reports what they actually experienced on their
phones over the last 28 days. It’s the truest measure of what your customers feel, so it comes
first when Google has it.
Performance score
Google’s 0 to 100 summary of one test load on an emulated mid-range phone over a slow 4G
connection. 90 and above is good; under 50 is poor. It’s useful for finding causes, and it moves
a little from one run to the next.
Main image or headline on screen
Largest Contentful Paint: how long until the biggest thing on the screen, usually the hero
or product photo, appears. Good is 2.5 seconds or less.
Time the page is frozen
Total Blocking Time: how long scripts keep the phone too busy to answer a tap while the page
loads. Good is 200 milliseconds or less.
How much the page jumps
Cumulative Layout Shift: how far things move as late content pushes them around. Good is 0.1
or less.
Response to a tap
Interaction to Next Paint, from real shoppers only: how long the page takes to respond after
a tap. Good is 200 milliseconds or less.