Is your internet slow, and how can you test its speed?

A video keeps buffering, but your router shows full signal. Is your internet plan too slow, or is the problem somewhere else? A speed test gives you a starting point. It measures the connection between your device and a test server at that moment, so it helps you investigate, but it does not diagnose every network problem.

To test your internet speed, connect to the network you want to check, pause large downloads and run a trusted speed test in your browser or app. Note the download speed, upload speed and latency, then repeat the test. If you are using mobile data, remember that the test itself consumes data.

What a speed test tells you

The three main results measure different things:

• Download speed is how quickly data comes to your device. It affects activities such as downloading files and watching video.
• Upload speed is how quickly data leaves your device. It matters when sending large files or joining a video call.
• Latency, often called ping, is the delay in a round trip between your device and a server. It is measured in milliseconds. A high delay can make calls and games feel unresponsive even when download speed looks reasonable.

Speeds are usually shown in megabits per second, written as Mbps. A file size may be shown in megabytes, written as MB. They are not the same unit: eight megabits equal one megabyte. In ideal conditions, a 40 Mbps connection has a theoretical maximum of about 5 MB per second, before accounting for overhead and other limits.

A speed test is not a promise that every website will load at that speed. The service you are using, the time of day, your device and other people on the network can all affect the result.

Get a useful result on your phone

1. Connect to the Wi-Fi you want to test. If you want to measure mobile data instead, turn Wi-Fi off and confirm the mobile network is active.
2. Pause app updates, streaming and large downloads on your phone. If you can, ask others on the same connection to pause heavy use for a few minutes too.
3. Open a reputable test service, such as Speedtest by Ookla or Fast.com, in your browser or its official app.
4. Start the test and wait for it to finish. Record the download speed, upload speed and latency if the service displays them.
5. Run it again after a short break. If the results differ widely, try another time of day and note what else was using the connection.

On mobile data, check your balance first if your bundle is small. A speed test transfers data in both directions, and the amount varies with the service and connection. Repeating it many times can use a noticeable part of your allowance.

Avoid any website asking for your bank details, router admin password or an unnecessary app download just to run a speed test. A browser-based test should not need those details.

Test a laptop or desktop

The steps are similar. Connect the computer to the network, close large downloads and run a test in the browser. If your router and computer support Ethernet, a wired test can help separate a Wi-Fi coverage problem from the connection reaching the router.

For a fair comparison, use the same computer and test service where possible. Try the wired connection first, then test over Wi-Fi near the router. A cable or Ethernet adapter can have its own speed limit, so an unusually low wired result is not automatically proof that the provider is at fault.

If you cannot use a cable, compare two Wi-Fi positions instead. Test near the router, then in the room where the connection feels weak. Do not stand so close that the device is pressed against the router; a normal nearby position is enough for a useful comparison.

How to read the results

Suppose your test shows 25 Mbps download, 5 Mbps upload and 40 ms latency. The download figure tells you the approximate rate measured from the test server to your device. The upload result describes the reverse direction. The latency figure describes delay; for this measure, lower is generally better.

Whether those numbers are enough depends on what you do and how many devices are using the connection. A single person reading web pages may need less capacity than a household with several video calls, streaming devices and uploads at the same time. The quality selected in a streaming app and the demands of each service also matter.

If downloads look fine but a video call keeps freezing, look at upload speed and latency as well. If a large file is uploading while someone else is on a call, pause the upload and see whether the call improves. This is a practical test, not a guarantee that upload is the only cause.

If one website is slow but other services work, the website itself or its connection may be the issue. A test server is not the same as the server hosting the site you are trying to use.

Why the result can be lower than your plan

Your package may advertise a maximum or an expected range rather than a speed guaranteed on every device. Read the plan’s terms and check whether your provider states a minimum or a typical speed. Then compare like with like: a Wi-Fi test in a distant room is not the same as a wired test at the router.

Common reasons for a lower result include:

• Other devices downloading, streaming or updating at the same time.
• A weak Wi-Fi signal, thick walls or a crowded wireless environment.
• A phone, computer, cable or router that cannot use the plan’s full speed.
• Mobile network congestion or a weak mobile signal.
• A temporary provider or test-server problem.
• A data-plan limit or speed reduction described in your provider’s terms.

A VPN can also affect the route and the result. If it is safe and appropriate to do so, compare a test with and without it. Do not disable a work VPN if your employer requires it.

What to do when the result is slow

Start by restarting the affected phone or computer and checking whether another device has the same problem. If all devices are slow, restart the router using its normal power controls and wait for it to reconnect. Do not press and hold the factory-reset button: that can erase its settings.

Next, compare the result near the router and in the room where you usually use the internet. If it improves near the router, try a more open, central position. Our guide on boosting a weak Wi-Fi signal explains what to check before buying equipment.

If the result stays poor near the router or over Ethernet, repeat the test at different times. Keep the results, your plan details, the device used and the time of each test. Contact your provider through its official support channel and share those notes. Ask whether there is an outage or a problem affecting your line, rather than assuming the router needs replacing.

You can also check the devices connected to your Wi-Fi if you suspect the connection is being shared more widely than expected. An unfamiliar device name is not proof of an intruder, so identify it before blocking anyone.

One test is a snapshot. A few consistent tests, taken under comparable conditions, give you a much better basis for deciding what to do next.