How to compare internal and external storage

You want to know whether an external drive is slower than your computer’s internal storage, or whether a connection is holding it back. Browser tests can help, but the two tests measure storage in different ways, so their scores are not a direct head-to-head comparison.

Use the Storage Test for browser-managed storage, then the USB & SD Speed Test for a flash drive or memory card. The results can show how each performs in its own test and help you find a bottleneck.

Compare the storage

1. Open the Storage Test and run it before connecting or disconnecting drives. Note the large-file read and write speeds and the small-write result.
2. Connect the external drive directly to the computer, if possible. Avoid a dock or hub for the first comparison, and make sure the drive is mounted and available.
3. Open the USB & SD Speed Test and test the external device. Note its read and write results, along with the connection you used, such as a USB port or card reader.
4. Run each test two or three times under similar conditions. Close apps that are downloading, syncing or copying files, and wait until the drive is idle between runs.
5. Compare read with read and write with write within each test. Treat the two tools’ numbers as separate measurements, not as a single ranking of the internal and external drives.

The Storage Test uses browser-managed storage. It does not give you a raw-disk benchmark or let you choose a particular internal drive or partition. Its result usually reflects the storage backing the browser profile, which may not be the exact device you intended to measure. The USB & SD Speed Test is the more useful check for the removable drive itself.

What the result means

The external drive is slower, but its results are steady

This can be normal. A flash drive, card reader, cable or USB port may be slower than the computer’s internal SSD. The external result also depends on the drive’s design and the kind of work the test performs. A steady result is more useful than a single peak number when you want to know what to expect in regular use.

The external drive’s speed changes sharply between runs

Other work may be using the drive, or the connection may be unstable. Some drives also slow after a short burst of fast writes. Repeat the test after the drive has been idle, then try a direct port and a different cable or reader if the result still varies.

The Storage Test is unexpectedly slow

This does not automatically mean the internal drive is failing. The browser may be busy, its storage area may have limited space, or the computer may be handling updates and background tasks. Check available space and repeat the test after closing other demanding apps.

The browser cannot run or complete a test

A browser permission, storage restriction or compatibility limit may be stopping the test. Review what browser storage permissions mean for a disk test, then retry in a current browser with the required access allowed.

How to get a more reliable comparison

1. Free up some space. A drive that is nearly full can behave differently, and a browser may not have enough room for its test. On Windows 11, check Settings › System › Storage. On macOS, check System Settings › General › Storage.
2. Use the same connection each time. Keep the external drive in the same port and use the same cable or card reader. If a hub is part of your normal setup, test directly first, then repeat through the hub to see whether it changes the result.
3. Pause background transfers. Stop cloud syncing, downloads, backups and other file copies before testing. These tasks compete for drive time and can make results jump around.
4. Keep power conditions consistent. A laptop may reduce performance on battery or in a power-saving mode. On Windows 11, check Settings › System › Power & battery. On macOS, check System Settings › Battery. Use the same power arrangement for every run.
5. Check the drive in another port or computer. If the external result remains much lower than expected, change one part of the connection at a time. A different port, cable or card reader can help identify the weak link.
6. Check for drive errors. If the device disconnects, produces errors or becomes slow across several computers, back up important files before doing more tests. Use the operating system’s disk checking tools, or contact the drive maker if the problem continues.

Why the numbers are not directly comparable

A browser test cannot access a drive like a dedicated system benchmark can. The Storage Test works through the browser’s storage area, while the USB & SD Speed Test measures a removable device using its own method. They may use different file sizes, write patterns and caching behavior. A cache is a temporary holding area that can make a short test look faster than sustained copying.

For a practical check, use both tools to establish repeatable results, then try the external drive with the kind of files you actually handle. Large video files and folders full of small documents can transfer at very different rates. The browser tests help you compare conditions and spot changes, but they do not diagnose every drive fault or prove the maximum speed printed on its packaging.

The tests work with local storage and do not upload your personal files.