How to test internet throughput with a proxy enabled

Your internet seems slower with a proxy turned on, but it is hard to tell whether the proxy is responsible. A speed test can measure the connection used by your browser, as long as the test traffic actually travels through the proxy.

Use the Speed Test to check download speed, upload speed, ping, and jitter. Compare repeat runs with the proxy enabled and, if you are allowed to, disabled. The difference can help you identify a slow proxy route, a busy network, or a result that varies naturally.

Test throughput through the proxy

1. Open the Speed Test in the same browser where the proxy is enabled. If you use a browser extension, check that it is active for the test page.
2. Pause downloads, cloud backups, video streams, and other activity that could use the connection. Keep the device in the same place and use the same network for each run.
3. Start the test and let it finish. Note the download speed, upload speed, ping, and jitter. Throughput is the amount of data transferred over time, usually shown in Mbps.
4. Run the test two more times with the proxy still enabled. Record each result rather than relying on one run, since network traffic and proxy load can change from minute to minute.
5. If policy allows, repeat the tests with the proxy off, then restore it. Keep the browser, device, network, and test timing as similar as possible.

A browser speed test measures the route between the browser and the test server. It does not automatically prove that the proxy handled the test. Some proxy extensions apply rules by website, and some configurations exclude particular destinations. Check the proxy's status, settings, or administrator logs if you need to confirm that this page is routed through it.

What the result means

Proxy-on and proxy-off speeds are similar

The proxy may have little effect on throughput for this test, or the test traffic may not be going through it. Confirm the route before concluding that the proxy has no impact. Also remember that other apps may use a different proxy configuration than your browser.

Speed is consistently lower with the proxy

The proxy route may add a bottleneck. The proxy server could be busy, far from you or the test server, or limited by its connection capacity. Encryption and the extra network hop can also add work and delay. A speed test identifies a difference, but it cannot tell you which part of the proxy service caused it.

Results change a lot between runs

Variable results can come from a busy proxy, Wi-Fi interference, other users on the network, or background traffic. Compare several runs and look at ping and jitter as well as download and upload speed. A high result in one run does not rule out brief slowdowns.

The test will not start or gives a very low result

The proxy may block the test connection, require a sign-in, or have a rule that prevents large transfers. A security filter can also interrupt a test request. Check the proxy's messages or ask its administrator whether browser-based speed tests are permitted before changing settings.

How to get a more reliable result

1. Use the same browser and route. A system proxy, browser setting, and extension can each route traffic differently. Keep the same browser and proxy configuration for all runs, and confirm that the test page is included in the proxy's rules.
2. Check the configured proxy. On Windows 11, open Settings › Network & internet › Proxy. On macOS, open System Settings › Network, select your active connection, choose Details, then Proxies. These screens show system proxy settings, but a browser extension can use separate settings.
3. Stop competing transfers. Pause software updates, file syncing, downloads, and video streams on the device. If other people are using the same connection, note that their activity can affect results too.
4. Repeat at a different time. If the proxy is shared, its load may peak at busy times. Compare several runs now and later, using the same device and setup.
5. Ask before changing a managed proxy. Work, school, and public networks may require a proxy for access or security. Do not bypass its rules. Ask the administrator whether the test is allowed and whether the proxy has a known bandwidth limit.
6. Check the connection without Wi-Fi variables. If you can do so safely and your network allows it, connect by Ethernet and repeat the test. If the result improves, Wi-Fi may be part of the problem rather than the proxy alone.

What this test can and cannot tell you

The result reflects the browser's connection to the Speed Test server at that moment. With a proxy, the measured route may include your device, the proxy, and the test server. A slow result could come from any part of that route, and ping may increase because the proxy is farther away or adds another network hop.

The result is not a direct measurement of your internet plan or the proxy's maximum capacity. A proxy can treat different websites, protocols, or types of traffic differently. Your normal app may also connect through another route. Use a test page that follows the same proxy rules as the traffic you want to investigate, and compare like with like.

The Speed Test exchanges test data with TooLab's server to measure the connection. Avoid running it while you need every bit of bandwidth for a call or other time-sensitive task.