Why does your real Data Capacity not match Advertised Storage?

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You’ve just bought a 1TB SSD and you want to show it to everyone. However, when you check the properties, you see the storage capacity of SSD display in Windows, which is always lower than the number announced by the manufacturer.

The question is whether the company cheats on you or you buy the wrong product? Why does your real Data Capacity not match Advertised Storage?

Why does your real Data Capacity not match Advertised Storage?

Luckily, the answer is no.

The difference is simply due to the expression between the two coefficients. Yet it also causes misconception and makes us confused.

Particularly, manufacturers usually use the decimal system to announce their products’ storage; while the OS apply the binary system, using only 0 and 1 to represent values.


For storage manufacturers, the capacity is calculated in decimal system and converted in the usual way. For example, 1 Terabyte (TB) = 10Gigabyte (1.000 GB) = 10Megabyte (1.000.000 MB). Whilst computers calculate in a different method, which is 1 Tebibyte (TiB) = 210 Gibibyte (1.024 GiB) = 220 Mebibyte (1.048.576 MiB).

Thus, 1 Mebibyte (MiB) is equal to 1,048576 Megabyte (MB) (note the comma to indicate the decimal value behind). In short, the storage is the same but the display values will vary when switching between standard SI or binary systems.


In order to calculate the number displayed in the operating system, you just take the amount that the manufacturer provided divided by 1,048576. The higher the storage capacity, the greater the difference.

For instance, my SSD Samsung PM961 256GB, Windows 10 only shows 237GB. Similarly, the Crucial MX500 1TB only has 931GB when checking its properties on a computer.


Have fun and hope you guys won’t confused about the aforementioned issue.