Free Internet Speed Test
Test download, upload, latency and jitter worldwide against your nearest Cloudflare edge, Cloudflare's network or Measurement Lab servers in 80+ countries.
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How to test your internet speed, latency and jitter
Measure download and upload speed, latency and jitter from anywhere in the world against your nearest Cloudflare edge, Cloudflare's speed network or Measurement Lab servers in over 80 countries.
- Close large downloads, video calls and streaming on this device and, if possible, on others sharing the connection.
- Pick a test server: ToolWorld Online at the nearest Cloudflare edge, Cloudflare's public speed network, or a Measurement Lab (M-Lab) server. To test a route abroad, pick a country such as South Korea, Germany, India or Brazil in Measurement Lab server location first. Then choose 8 or 10 seconds per direction and, for Cloudflare servers, the number of parallel connections.
- Select Start speed test. Latency is measured first with 20 small requests, then download, then upload.
- Read download and upload in Mbps, latency and jitter in milliseconds, and the server or edge location that answered.
- Copy the result, or run it again against a different server to see whether a slow result is your connection or one route.
When an internet speed test is useful
A speed test gives you numbers to work with when a connection feels slow. Video calls that freeze, cloud backups that crawl and games that stutter each point to a different problem, and download speed, upload speed, latency and jitter help tell them apart. Download matters for streaming and large files, upload matters for video calls and sending files, latency matters for anything interactive, and jitter shows how steady that latency is.
It is also a quick way to compare setups. Running the test on Wi-Fi in the living room, on Wi-Fi next to the router and on a network cable shows whether the wireless link is the bottleneck. Running it before and after restarting a router, changing a Wi-Fi channel or switching providers gives you a before and after you can actually compare.
By default this test measures the path from your browser to the nearest Cloudflare edge location, where ToolWorld Online's server runs, and you can switch to Cloudflare's speed network or a Measurement Lab server to compare routes. Cloudflare and Measurement Lab both run servers on every inhabited continent, so the test works the same from Seoul, Lagos, Berlin, Mumbai or São Paulo. The Measurement Lab location list also lets you test against another country on purpose, for example to see how well your connection reaches servers in South Korea or Germany. That is close to most users, so it reflects your local connection well, but it is not a test of one specific website or game server.
Worked example: reading a result
Suppose the download phase runs for 10 seconds and the tool ignores the first 1.5 seconds while the connections ramp up. If 53 MB arrive during the remaining 8.5 seconds, the download speed is 53,000,000 bytes times 8 bits, divided by 8.5 seconds, which is about 49.9 million bits per second, shown as 49.9 Mbps.
For latency, imagine five of the round trips took 18, 22, 19, 25 and 20 milliseconds. Sorted, the middle value is 20, so latency is 20 ms. Jitter is the average change between consecutive samples: the changes are 4, 3, 6 and 5 ms, which add up to 18, and 18 divided by 4 gives a jitter of 4.5 ms. The real test uses 20 samples, but the arithmetic is the same.
A result such as 49.9 Mbps down, 9.8 Mbps up, 20 ms latency and 4.5 ms jitter is comfortable for HD streaming and video calls. Upload near 1 Mbps or jitter above about 30 ms would explain choppy calls even when download looks fine.
How the test works
Latency comes first. The browser sends 21 tiny requests one after another, discards the first because it includes connection setup, and reports the median of the remaining 20 so a single slow request does not distort the figure.
For download, the browser opens several parallel connections and repeatedly requests blocks of random data from the edge server, counting bytes as they arrive. Block sizes grow with the measured speed, up to 25 MB per request. Upload works the same way in reverse, sending random data that the server reads and discards. Each direction runs for the length you choose, and the reported speed uses only the steady part after the warm-up. Nothing you send is stored.
Common mistakes when testing speed
The most common mistake is testing while something else is using the connection. A phone uploading photos, a game console downloading an update or another person streaming in 4K will take bandwidth away from the test. Pause what you can, or at least note it.
Another mistake is comparing a Wi-Fi result with a plan sold as a wired speed. Wireless signal, distance, walls and older devices can easily halve throughput. Test over a cable to check what your provider delivers, and over Wi-Fi to check your home network.
Finally, do not judge a connection on one run. Speeds change through the day as neighborhood traffic rises and falls. Run the test a few times at different hours, and remember that a test against a nearby edge server can look better than downloads from a distant site.
Useful tips and limitations
- Test from the same spot several times at different hours; a single run can be skewed by a background update.
- If Wi-Fi results are far below a wired test, the bottleneck is usually the wireless link, not your internet plan.
- Use the single-connection option to see how one download, like a large file from one server, is likely to perform.
- If latency is low when idle but calls still lag, check upload speed and jitter, which matter more for real-time audio and video.
Common questions
Which servers can the Internet Speed Test use?
You can test against ToolWorld Online's own server at the nearest Cloudflare edge, Cloudflare's public speed network, or Measurement Lab (M-Lab) NDT7 servers, the open network behind Google's search speed test. M-Lab servers are found near you automatically, or near any country you choose from the list. Results differ between servers because each takes a different route.
How much data does the Internet Speed Test use?
It depends on your speed. A 50 Mbps connection transfers roughly 60 MB down and a similar amount up in a 10-second test, while a gigabit connection can move several hundred megabytes. Avoid repeated runs on metered mobile data.
Why does the Internet Speed Test show less than my plan speed?
Advertised plans describe the line to your provider, while this test includes Wi-Fi, your router, other devices, browser overhead and the route to the edge server. Testing over a cable with other traffic paused usually gets closer to the plan.
Is the Internet Speed Test result the same as Speedtest or Fast.com?
Not exactly. Each service uses different servers and methods, so numbers differ slightly. This one lets you pick the nearest Cloudflare edge or a nearby Measurement Lab server, which are usually close to you.
Why does the Internet Speed Test ignore the first seconds?
New connections start slowly and speed up. Ignoring the first 1.5 seconds of each direction reports the steady speed your connection can sustain.
Does the Internet Speed Test store my IP address or results?
The test endpoint reads uploaded test data and discards it, and it does not save results. Requests are counted per IP address for a short rate limit. Results stay in your browser unless you copy them.
Depending on the server you pick, test traffic goes to the ToolWorld Online service, Cloudflare's speed service or Measurement Lab, which publishes its test data openly. No account is needed and ToolWorld does not store your results.