Internet speed test
A quick internet speed test: download and upload speed in Mbps, plus latency and jitter, measured against Cloudflare’s public test servers.
The test uses about 35 MB of data on Cloudflare’s public speed servers. Close other downloads for the most accurate result. Mobile data charges may apply.
About the internet speed test
A quick internet speed test: download and upload speed in Mbps, plus latency and jitter, measured against Cloudflare’s public test servers.
Part of SmartCalcy’s data & networking tools. It runs in your browser with no account, uses your own currency and units (change them at the top of the page), and gives estimates for information only, so check official guidance before you rely on a result.
How to use the internet speed test
What it calculates and when to use it
Measures the download speed, upload speed, latency and jitter of your connection from your browser, using Cloudflare’s public speed servers. It gives a quick check of whether your broadband or mobile data is performing as expected.
How to use it, step by step
- Close other downloads, streams and cloud backups.
- Press “Start test”.
- Wait while latency, download and upload are measured, about 15 to 40 seconds.
- Read the results, or press “Test again”.
What each input means
- Start test – Begins the measurement. There is nothing to enter.
How to read the results
- Download – How fast data arrives, in megabits per second (Mbps).
- Upload – How fast your device can send data, in Mbps.
- Latency (ping) – The shortest round-trip time to the server, in milliseconds.
- Jitter – How much latency varies between measurements, in milliseconds.
The formula
Speed in Mbps = bytes × 8 ÷ seconds ÷ 1,000,000. The test downloads files of 5, 10 and 15 MB and uploads files of 1, 2 and 3 MB, and reports the best run. Latency is the lowest of eight small requests, and jitter is the average difference between consecutive latencies.
A worked example
Downloading 15 MB in 1.2 seconds is 15 × 8 ÷ 1.2 = 100 Mbps.
Assumptions and limits
- The test uses roughly 35 MB of data, which matters on a mobile data plan.
- Results are to one server near you and can differ from other speed tests.
- Browser, Wi-Fi quality and other devices on your network all affect the result.
Common mistakes
- Testing over Wi-Fi from a far room and blaming the provider.
- Leaving video calls or downloads running during the test.
- Mixing up megabits (Mbps) with megabytes. Divide by 8 to get megabytes per second.
Frequently asked questions
What is a good internet speed?
For one person, 25 Mbps is enough for HD streaming and video calls. Households with several users usually want 100 Mbps or more.
Why is my speed lower than my plan?
Plans quote the best case on the line. Wi-Fi, other devices, the time of day and the test server all reduce results.
What is jitter?
Variation in latency. High jitter makes calls and games stutter even when speed is high.
How much data does the test use?
About 35 MB.
Why did the test fail?
An ad blocker, firewall or lost connection can block the test servers. Turn the blocker off for this page and try again.
Related tools
Results
- Download
- –
- Upload
- –
- Latency (ping)
- –
- Jitter
- –