Internet Speed Test
Measure your connection to the nearest Cloudflare edge — download, upload, latency and jitter — right in your browser. No account, no install, and the result exports as CSV.
An internet speed test measures four things about the path between your device and one nearby test server: how fast data comes down, how fast it goes up, how long a round trip takes, and how steady that round trip is. This test measures your connection to the nearest Cloudflare edge, in your browser, using the open-source engine behind speed.cloudflare.com — and it shows every number with its meaning, instead of a single score. The companion article how to read speed test results explains what counts as good for browsing, video calls, gaming and 4K streaming, and why the same line gives a different number every run. If your address itself looks suspicious to other services, check the IP Purity Check; to see what websites learn from your browser as well as your connection, try the Browser Fingerprint Test; and to compare how your site answers from around the world, use Global Ping.
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Before you start
- Close other apps and tabs that use bandwidth — video streams, downloads, cloud backups and video calls all share the connection being measured, and they will lower the result.
- One full test can move up to about 200 MB of data (Cloudflare’s own figure). The test ramps through larger downloads and uploads until each direction has been measured properly, so it uses real traffic.
- Avoid running the test on a metered or capped connection, such as mobile data with a small allowance. Use an unmetered Wi-Fi or wired connection when you can, and prefer a wired connection for the most repeatable numbers.
🔒 The test runs in your browser against the nearest Cloudflare edge. Cloudflare collects the measurement results for aggregated insights; SysOSX stores nothing about your test. No account is needed.
Measurement powered by @cloudflare/speedtest (MIT licence), the open-source engine behind speed.cloudflare.com.
What happens to your test
The measurement runs between your browser and the nearest Cloudflare edge: your device downloads and uploads test data to speed.cloudflare.com, so Cloudflare sees your IP address and the measurements, as any server you connect to would. Measurement results are collected by Cloudflare on completion for the purpose of calculating aggregated insights regarding internet connection quality — that is the engine README’s own wording. After the test, this page shows your IP address, provider and rough location via the same whoami endpoint the Browser Fingerprint Test uses, with at most one request per page load, and nothing about the test is stored by SysOSX: no account, no history, no identifier beyond the rate limit. The CSV export is built in your browser and downloaded directly; it is never sent anywhere.
What this test does NOT prove
A result is an estimate of your connection to the nearest Cloudflare edge, at this moment, from this browser, over this Wi-Fi or cable. It is not a guaranteed line rate, and it is not a verdict on your provider: the same line gives different numbers every run, because Wi-Fi, other devices, the time of day and the browser itself all shape the result.
Speeds are shown in Mbps — megabits per second. To compare with a download shown in MB/s (megabytes per second), divide by 8: 80 Mbps is about 10 MB/s. The dashboard shows both, so the two units are never confused.
A speed test cannot diagnose why a connection is slow. It cannot tell a Wi-Fi problem from a provider problem, congestion from throttling, or a slow server from a slow line — and it does not measure packet loss in this version, because that needs a TURN relay this site has not set up. The article how to read speed test results explains how to narrow it down, including repeating the test wired, at different times, and three times in a row.
How the test works
The test runs in rounds. It starts with small downloads and uploads and ramps up through larger payloads — 100 KB, 1 MB, 10 MB, 25 MB, 100 MB and up to 250 MB — stopping early in each direction once a round takes a full second, which is why a fast connection finishes with larger transfers than a slow one. Bandwidth is reported at the 90th percentile of the samples, latency at the median, and latency is also sampled while downloads and uploads are running, which shows how much the connection slows down under load.
Timings come from the browser’s PerformanceResourceTiming API, which measures each request from the browser’s own clock — so the result includes the limits of your browser and Wi-Fi, not just the line. Because the test server is the nearest Cloudflare edge, a result says most about the first part of the path; a site hosted far away, or behind a slow server, can still feel slow when this test looks fast. Run the test three times and compare the middle result if you need a number you can quote.
Frequently asked questions
Why do repeated tests give different numbers?
Because almost everything between you and the test server changes between runs: Wi-Fi signal, other devices and apps sharing the connection, the time of day, and which edge server answers. Browsers also cap what a single page can push through. Treat one run as a snapshot: close other apps, run the test three times, and compare the middle result. The article how to read speed test results explains each source of variation.
Why is my result slower than the speed my plan advertises?
An advertised speed is the line’s maximum under ideal conditions — usually wired, with nothing else using the connection. A browser test over Wi-Fi measures the whole path your device actually uses, including Wi-Fi, the browser and the route to the nearest edge, so it usually reads lower. If the gap is large, repeat the test on a wired connection with other apps closed: if the wired number is close to the plan and the Wi-Fi number is not, the Wi-Fi is the bottleneck, not the line.
Will this test use up my mobile data allowance?
It can use a lot of it: one full test can move up to about 200 MB. Do not run repeated tests on a metered connection. The test warns before it starts, and it never runs on its own — it only measures when you press “Start test”.