How to check speeds over a USB phone tether

Your laptop is online through your phone, but downloads or video calls feel slow. A speed test can show how the tethered connection performs, but it measures the complete path to the internet, not the USB cable by itself.

Use the Speed Test to check download speed, upload speed, ping and jitter. Then compare the result with a test on the phone itself to narrow down where the slowdown is happening.

Test your USB phone tether

1. Connect the phone to the computer with a USB cable that supports data, then unlock the phone. Open the Speed Test on the computer.
2. Turn on USB tethering on the phone. On Android, look under Settings › Network & internet › Hotspot & tethering › USB tethering. Menu names vary by phone. On an iPhone, open Settings › Personal Hotspot, turn on Allow Others to Join, and accept Trust This Computer if prompted.
3. Make sure the phone is using mobile data if you want to measure cellular service. Turn off the phone's Wi-Fi if you want to avoid testing an internet connection that comes from Wi-Fi instead.
4. Temporarily turn off the computer's Wi-Fi so it cannot use a separate wireless connection. Check that the computer still has internet access through the phone.
5. Run the Speed Test two or three times, leaving a short pause between runs. Note the download, upload, ping and jitter readings, and whether the results are consistent.
6. For comparison, run the same test on the phone using mobile data, in the same location. Keep other downloads, video streams and cloud backups paused during both tests.

A speed test exchanges test data with a server to measure the connection. Keep that in mind if your mobile plan has a data limit, especially if you repeat the test many times.

What the result means

The computer and phone get similar speeds

The tether is probably passing the available cellular connection through to the computer normally. If both tests are slow, the likely limit is the mobile signal, network congestion, your plan, or the test conditions rather than the USB connection.

The phone is fast but the computer is much slower

Check that the computer is really using the USB tether and not another network. A poor cable, a USB port problem, a VPN, security software or a computer network setting could also affect the result. Repeat the test after changing one thing at a time.

Download is good but upload is slow

Cellular networks and plans do not always provide matching download and upload speeds. Uploads may also slow down when another device or app is sending photos, backups or video. Check the phone's result as well: if upload is slow there too, the computer's USB link is less likely to be the cause.

Ping or jitter is high, or readings vary a lot

Ping is the response time between your device and the test server. Jitter is how much that response time changes. High or inconsistent readings can make calls and games feel delayed even when download speed looks adequate. Cellular signal changes, busy network conditions and background traffic can all contribute.

The computer loses internet when Wi-Fi is off

The computer may not have recognized the phone as a network connection, or tethering may not be active. Check the phone's tethering setting, unlock it, and reconnect the cable. If the computer keeps using Wi-Fi, a test might not reflect the USB tether at all.

How to fix a slow tether

1. Check mobile data and signal. Confirm that mobile data is on and the phone has a usable cellular signal. Move near a window or try another location, then test again. If the phone itself is slow in the same spot, changing the computer's USB settings is unlikely to help.
2. Confirm USB tethering is enabled. On Android, open Settings › Network & internet › Hotspot & tethering and enable USB tethering while connected. On iPhone, open Settings › Personal Hotspot and turn on Allow Others to Join. Names can differ by model and operating system version.
3. Check which network the computer is using. On Windows 11, open Settings › Network & internet and check the connection shown there. On macOS, open System Settings › Network and look for the phone connection. Temporarily turn Wi-Fi off in Settings › Network & internet › Wi-Fi on Windows 11 or System Settings › Wi-Fi on macOS, then confirm the tether still works.
4. Try another cable and USB port. Some cables only charge and cannot carry data. Try a cable known to transfer files, connect it directly to the computer instead of through a hub, and reconnect the phone while it is unlocked.
5. Pause other traffic. Stop large downloads, cloud backups and streaming on the computer and phone. If you use a VPN, test without it only if your work or security rules allow you to do so. A VPN can change the route and affect speed or ping.
6. Reconnect both devices. Turn tethering off, unplug the cable, restart the phone and computer, then connect and enable tethering again. If the computer still does not recognize the phone, check for operating system updates or contact the phone maker or carrier for device-specific setup help.

What the speed test cannot isolate

The test measures internet performance through the phone, cellular network, carrier routing and test server. It cannot report the USB cable's maximum transfer rate or prove that a cable is faulty. A slow result is not, by itself, evidence of a bad USB port.

To separate the likely causes, compare the computer's tethered result with the phone's mobile-data result, then repeat in another location or at another time. If the phone is consistently fast but the computer remains slow across a known data cable and different USB ports, check the computer's network configuration or ask the device maker for support.