Storage Converter
Convert digital storage capacities across decimal SI (powers of 10) and binary IEC (powers of 2) memory standards. Demystify why a 1 TB hard drive shows as only 931 GB in Windows disk management.
Magnitude of digital file or disk capacity
Origin digital data unit
Destination target data unit
Storage magnitude in requested target unit
How to Use This Calculator
- Enter the file or disk size quantity.
- Select your source data unit (e.g., Terabytes TB or Gigabytes GB).
- Select your destination conversion unit.
- Review the converted capacity and exact byte count.
Formula & Calculation Methodology
All digital capacities convert through the fundamental 8-bit Byte (B). The International Electrotechnical Commission (IEC) distinguishes decimal prefixes (1 KB = 1,000 B, 1 MB = 1,000,000 B) from binary prefixes (1 KiB = 1,024 B, 1 GiB = 1,073,741,824 B).
Worked Example
1 Terabyte retail hard drive capacity in decimal Gigabytes
500 Megabytes to binary Megabytes (MiB)
Frequently Asked Questions
Why does my 1 TB drive only show 931 GB in Windows?↓
Drive manufacturers advertise capacities in decimal units (1 TB = 1,000,000,000,000 bytes). Microsoft Windows measures capacity in binary GiB (1,024³ bytes), so 1,000,000,000,000 ÷ 1,073,741,824 ≈ 931.32 GiB, even though it labels the unit as "GB".
What is the difference between a bit (b) and a byte (B)?↓
One byte consists of exactly 8 bits. Internet connection speeds are almost always advertised in bits per second (e.g. 100 Mbps), whereas file downloads and storage are measured in bytes (100 Mbps download speed = 12.5 MB/s).
What is an IEC binary prefix?↓
IEC prefixes (KiB, MiB, GiB, TiB) explicitly denote powers of 2 (1,024, 1,024², 1,024³, 1,024⁴), preventing ambiguity with SI decimal prefixes (KB, MB, GB, TB) which represent powers of 10.
What is a limitation when converting raw disk drive capacity to usable storage?↓
Raw capacity conversions do not account for file system partitioning overhead (such as NTFS or APFS master file tables, sector alignment, and reserve blocks).
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Source Citation & Disclaimer
Informational tool only; not licensed tax, legal, or financial advice.