What to test before using a USB stick for system recovery

A USB stick can appear to have enough space and still fail when you need it most. Some drives have less usable storage than their label claims, while others cannot reliably read back data they just wrote.

Test the stick before putting recovery files on it. The Fake USB & SD Check writes test data to the drive and reads it back to check its usable capacity. After that, you still need to make the recovery media and confirm it starts on the computer you may need to repair.

Test the USB stick first

1. Open the Fake USB & SD Check in Chrome or Edge on a computer. This tool does not work fully in every browser, and it is not a phone test.
2. Connect the USB stick you plan to use. Follow the tool's prompts to select the drive and begin the check. Make sure you have selected the right device.
3. Let the test finish writing data and reading it back. Do not unplug the stick or let the computer go to sleep while the test is running.
4. Check the reported usable size and whether the read-back completed without errors. If the check fails, do not put your only recovery copy on this stick.

Treat this as a real write test. Use a blank stick, or copy important files somewhere safe first. Run the test before creating recovery media, because the recovery setup may erase the drive, and testing a drive afterward may interfere with the recovery files.

What the result means

The test completes and the usable size looks right

The stick was able to store and read back the tested data, and its usable capacity is consistent with what you expect. This is a good sign, but it is not a guarantee that the drive will never fail or that it can boot your computer. A drive labeled 64 GB may appear as about 59 GB in some displays because manufacturers and operating systems can report capacity differently.

The usable size is much smaller than the label

The stick may be counterfeit, damaged, or reporting a problem. A fake oversized drive can accept data at first, then overwrite earlier data when you go beyond its real capacity. Do not trust it with recovery files or backups. If you bought it recently, keep the test result and contact the seller about a return.

The read-back fails or the test stops

The drive could not reliably store and retrieve the test data. A loose connection, USB hub, port problem, or failing flash memory can cause this. Reconnect it directly to another port and test again. If it fails again, replace the stick rather than relying on it for recovery.

The test is slow but completes

Slow performance alone does not prove that the drive is fake or broken. Older or inexpensive sticks can write slowly, and the test takes longer when it has to write and read a large amount of data. For recovery, a slow stick may be inconvenient, but repeated read-back errors are a stronger reason not to use it.

Prepare and verify the recovery stick

1. Check the recovery media requirements. Use a stick with at least the capacity required by the recovery creator or device manufacturer. Leave extra room if the instructions recommend it. Do not assume that every recovery image fits on the same size drive.
2. Create the recovery media after the test. Follow the instructions for the computer or operating system you need to recover. Some recovery creators format the USB stick, so save anything important elsewhere first.
3. Eject the stick safely. Use the computer's eject option before unplugging it. This reduces the chance of interrupting a final write.
4. Start the computer from the USB stick. Use the computer maker's instructions to open its startup or boot menu and select the USB device. The key or startup method varies by model.
5. Stop at the recovery screen. Confirm that the recovery environment or installer opens, then exit without choosing a reset, restore, or reinstall option. Starting successfully is a separate check from confirming the stick's capacity.

If the USB stick is not listed in the startup menu, check that the recovery media was made for that computer and that the creation process completed. A capacity test cannot fix an incompatible recovery image or a firmware setting that prevents external booting.

What the capacity test cannot prove

The Fake USB & SD Check looks for a mismatch between the drive's claimed capacity and the amount of data it can actually store and read back. It does not create recovery media, verify that recovery files are correct, or prove that your computer can boot from the stick.

For a bootable Windows installer, follow a separate boot check after creating it. The guide How to test a USB stick for a bootable installer explains how to check that part without proceeding with an installation.

Keep a second recovery option if the computer is important, such as another tested USB stick or the manufacturer's supported recovery method. A USB test is useful evidence, not a promise that one small drive will be available when an emergency happens.