Mobile Website Speed Test
Test how fast your website loads on a phone. This free mobile website speed test loads your page in a real Chrome browser as a mobile device on a 4G or 3G network, from locations around the world, and shows what slows it down.
At a glance
- Real mobile emulation: Chrome with a Pixel 8 screen (412 × 915, 2.625× pixel ratio), touch and an Android user agent.
- Mobile networks: 4G (170 ms latency, 9 Mbps) is preselected; 3G (300 ms, 1.6 Mbps down) and Broadband are available.
- Metrics: load time, TTFB, Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), Total Blocking Time (TBT), FCP and Speed Index.
- Lighthouse: mobile performance, accessibility, best-practices and SEO scores with specific fixes.
- Visuals: filmstrip, page-load video and a full-page mobile screenshot.
- Global: test from up to 3 locations at once without an account.
- Free: no sign-up needed; a free account adds up to five locations per test and test history.
How to test your mobile website speed
- Enter the URL of your page. Mobile and 4G are already selected.
- Switch the network to 3G to see how the page behaves on a slow connection.
- Choose up to three locations near your visitors.
- Click Run Test and watch the results arrive from each location.
Why mobile page speed matters
Most web traffic now comes from phones, and Google indexes and ranks pages based on their mobile version. Phones have slower CPUs than desktops and cellular networks add latency to every request, so a page that feels instant on office Wi-Fi can take several seconds on 4G. Slow mobile pages lose visitors: every extra second of load time increases the share of people who leave before the page appears.
What the mobile speed test shows
- Core Web Vitals in the lab: Largest Contentful Paint and Cumulative Layout Shift, plus Total Blocking Time as the lab stand-in for Interaction to Next Paint.
- Waterfall: every request with DNS, connect, TLS, waiting (TTFB) and download time, so you can see which images, scripts or third parties are heavy on mobile.
- Filmstrip and video: exactly what a mobile visitor sees while the page loads, frame by frame.
- Errors: failed requests and JavaScript console errors that only appear on the mobile layout.
- Comparison by location: TTFB, load time, LCP, CLS, TBT, page size and requests side by side.
Mobile speed targets
| Metric | Good on mobile |
|---|---|
| Largest Contentful Paint (LCP) | Under 2.5 s |
| Cumulative Layout Shift (CLS) | Under 0.1 |
| Total Blocking Time (TBT) | Under 200 ms |
| Time to first byte (TTFB) | Under 0.8 s |
| Page weight | As small as possible; under 2 MB is a reasonable goal |
LCP, CLS and TTFB targets are Google's "good" thresholds.
How to speed up a mobile website
- Serve responsive images sized for small screens, in WebP or AVIF.
- Ship less JavaScript: split bundles, defer non-critical scripts and remove unused libraries.
- Inline critical CSS and preload the LCP image and fonts.
- Reserve space for images, ads and embeds so the layout does not jump.
- Use a CDN so phones download from a nearby server.
Related free tools
- Website Speed Test: the same test with desktop defaults.
- Web Server Test: check server response time on its own.
- China Firewall Test: test your mobile page from inside mainland China.
For continuous mobile performance monitoring with alerts, see Dotcom-Monitor.
Frequently asked questions
Is the mobile website speed test free?
Yes. You can test any public page from up to three locations without signing up. A free account adds up to five locations per test, test history, sharing and test comparison.
Does the test use a real phone?
No. It uses a real Chrome browser with accurate mobile emulation: a Pixel 8 screen size and pixel ratio, touch input, an Android user agent and mobile network throttling. This gives repeatable results from any location.
Which mobile network speeds can I test?
4G (170 ms latency, 9 Mbps), 3G (300 ms latency, 1.6 Mbps down, 768 kbps up) and Broadband (20 ms, 20 Mbps down). You can also turn throttling off to see the page at full connection speed.
What is a good mobile page load time?
Aim for a Largest Contentful Paint under 2.5 seconds on 4G, which is Google's "good" threshold. If your LCP is above 4 seconds, mobile visitors are likely leaving before they see your content.
How is this different from Google PageSpeed Insights?
PageSpeed Insights runs one mobile Lighthouse test from a Google data center. This test lets you choose the locations and the network speed, runs them side by side, and adds a full waterfall, a filmstrip and video, failed requests and console errors.
What is the difference between website speed and page speed?
Page speed is how fast one page loads. Website speed is the overall speed across your site's pages. Test your most important pages one at a time: the home page, top landing pages and checkout.
How often should I test my mobile site speed?
After every significant change, such as new images, scripts, themes or plugins, and at least monthly. For constant checks with alerts, use a monitoring service.
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