Is missing drive space caused by bad sectors or fraud?

No. It is purely a mathematical difference between Decimal (base-10) and Binary (base-2) measurement units.

Updated: August 2026 • Verified v1.2

Usable Drive Storage & Format Capacity Calculator

Hardware & SystemsHardware

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Usable_GiB = (Advertised_GB * 10^9) / (1024^3) * (1 - FS_Overhead%)

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Understanding Your Results

Calculates real Windows reported GiB/TiB capacity, decimal byte totals, file system table overhead (NTFS, APFS, ext4), and practical file capacity (4K movies, RAW photos, songs).

Practical Guidance & Next Steps

Drive manufacturers market in decimal base-10 ($10^9 = 1,000,000,000$ bytes = 1 GB), while Windows measures in binary base-2 ($2^{30} = 1,073,741,824$ bytes = 1 GiB), causing an apparent ~7% to 9% reduction.

What is this?

A hardware storage utility that converts advertised decimal drive sizes into real formatted operating system capacity.

How does it work?

1. Enter advertised drive capacity (e.g. 1 TB) or pick a preset. 2. Choose file system format (Windows NTFS, macOS APFS, Linux ext4). 3. View actual reported space in Windows and estimates of how many 4K movies and photos fit.

Why use it?

Eliminates buyer confusion over 'missing' hard drive space and helps plan storage needs accurately.

Technical Scope & Calculation Limitations

Actual file system overhead depends on drive cluster allocation size and partition table layout.

Frequently Asked Questions

Drive makers define 1TB as 1,000,000,000,000 bytes (decimal). Windows calculates 1GB as 1,073,741,824 bytes (binary). Dividing 1,000,000,000,000 by 1,073,741,824 yields 931.32 GiB.

Windows Desktop & Widget Options