SD Card Tester: Real Capacity

Is your SD card really as big as the label says? Fake and counterfeit memory cards and USB sticks report a capacity they do not have. SD Card Tester checks what the card can actually hold.

HOW IT WORKS

• The app writes test patterns to the card and reads them back, then compares the result with the capacity the card claims.
• Capacity check: places markers across the whole claimed capacity. On most cards (FAT32 or exFAT), Android fills the whole card to do that, so the writing takes as long as the Full test. It is faster overall only because it reads back only those markers: a solid capacity check, not a test of every block.
• Full test: writes the free space on the card completely and reads all of it back. Slower, but far more thorough. It works like the classic desktop capacity testers.

WHAT YOU GET

• A clear verdict: Capacity confirmed, Capacity overstated, Blocks failing, or No verdict when a test could not finish. Every result says what the test did and did not prove.
• Test history: results are kept on your device.
• Share or save the report as an image, free.
• Works with SD and microSD cards (card slot or USB card reader) and, on phones that allow it, USB flash drives over OTG.

PRO (ONE-TIME PURCHASE)

• Full test history
• PDF report
• Test several cards one after another
• No ads

Remove ads is a separate one-time purchase for ads only; Pro already includes no ads. Both test modes and every verdict are free. Nothing about the result is locked.

PRIVACY

Your measurements, results and history stay on your device. Only ads, purchases, and usage and crash statistics use the internet; no card name, file or measurement is ever sent.

GOOD TO KNOW

• The Capacity check tests capacity at the points it samples, not every byte, and says nothing about reliability.
• Both tests can take a long time on large cards: on most cards even the Capacity check writes the whole card.
• Android asks you to choose a folder on the card so the app is allowed to write to it.
• Some phones do not show USB drives to apps.

SD and microSD are trademarks of SD-3C, LLC.