USB drive reads faster than it writes through a hub

Your USB drive copies files to the computer quickly, but saving files to it takes much longer. That difference can come from the drive itself, the hub, the cable, or the way the speed test runs. A read speed higher than a write speed is common, but a sudden drop or a very low write result is worth checking.

Compare both directions under the same conditions with the USB & SD Speed Test. Then use the checks below to find out whether the hub is limiting the drive or the difference is normal for that device.

Compare the drive's read and write speeds

1. Connect the USB drive or memory card to the hub you want to check. Close apps that may be copying or scanning files in the background.
2. Open the USB & SD Speed Test and follow its on-screen prompts to select the removable drive or card.
3. Run both the write and read measurements. Keep the same drive, hub port, cable, and computer connected for both.
4. Repeat the measurements two or three times. Note whether the results are similar or whether the write speed falls sharply after the first run.

Back up important files before running any write-speed test. If the browser asks for access to the drive, grant it for the test. Do not unplug the drive while a measurement is running.

What the result means

Read speed is higher, but write speed is steady

This is often normal. Many flash drives can read data faster than they can save it. The drive's memory and controller, available free space, and type of files being written can all affect write speed. A gap by itself does not prove the hub is faulty. For more context, see why USB drives read faster than they write.

Both speeds are much lower than expected

The connection may be using a slower USB mode, or another part of the setup may be limiting it. A USB 3 hub cannot make a USB 2 drive run at USB 3 speeds. The computer's port, the hub's upstream cable, and the drive all need to support a compatible faster mode.

Write speed starts high, then drops

Some drives use a fast temporary memory area and slow down after it fills. This can happen during large or repeated writes, even when the hub is working properly. Compare results over more than one run and avoid judging the drive by only its first short burst.

Results change a lot between runs

Background file activity, antivirus scans, other devices using the hub, and the drive's temperature can affect measurements. Browser-based tests also measure a real workload through the current setup, not a guaranteed maximum speed printed on a package.

How to fix slow USB write speeds

1. Try another port on the hub. Keep the drive and cable unchanged. If one port is consistently slower, the issue may be limited to that port or its connection.
2. Check the hub and cable ratings. Confirm that the hub supports USB 3 and that its computer-facing cable is suitable for that speed. A USB 3-shaped connector does not guarantee a USB 3 data connection. Check the hub's markings or product information rather than relying only on the connector color.
3. Disconnect other devices from the hub. Storage devices and other peripherals may share the hub's connection to the computer. Unplug devices you do not need, then repeat the same test.
4. Connect the hub to a different computer port. Use a USB 3 port on the computer if available. Avoid chaining one hub through another while testing, since each added connection can introduce another limit.
5. Test the drive without the hub. Connect it directly to a USB 3 port on the computer, using the same cable if it is detachable. If writing becomes much faster, the hub, its cable, or the hub's shared workload is likely involved.
6. Test on AC power and reduce background work. On Windows 11, open Settings › System › Power & battery and choose a performance-oriented power mode if one is available. On a Mac laptop, open System Settings › Battery, connect the charger, and turn off Low Power Mode if it is enabled. Close large downloads, backups, and file scans before repeating the test.
7. Check free space before considering a format. A nearly full drive can write more slowly. If you decide to reformat it, copy its files somewhere safe first, since formatting erases the drive.

When the drive or hub may be faulty

Repeat the comparison with another known-good USB drive, and test your original drive directly on the computer. If several drives write slowly only through one hub, the hub or its cable is a stronger suspect. If one drive is slow through multiple ports and on another computer, the drive itself may be the limit or may be failing.

Replace a hub if its ports disconnect, become unusually hot, or consistently perform poorly with multiple devices. If a drive disconnects during writes, makes important files disappear, or reports errors, stop using it for important data and make a backup before further testing. A speed test cannot repair a damaged drive or establish its long-term reliability.

Why hub results can vary

A hub shares its connection to the computer among its ports. If several devices transfer data at once, they may compete for that shared link. A powered hub can help when connected devices need more power, but external power does not automatically make data transfer faster. The hub, upstream cable, computer port, and drive still need to support the faster USB mode.

Compare results in MB/s with other MB/s results. Internet speed plans are usually shown in Mbps, which uses different units: 8 megabits per second equal 1 megabyte per second. The USB test measures the setup you are using, so a repeatable comparison between hub and direct connection is more useful than one isolated number.