Data Storage Converter Guide: Bytes, KB, MB, GB, TB Explained

A single byte holds 8 bits, enough to represent one character like the letter A. Everything above that, kilobytes, megabytes, gigabytes, terabytes, is just a multiplier stacked on top of the byte, but the exact multiplier depends on whether you are using the decimal convention manufacturers use or the binary convention operating systems use, and that difference is exactly why your new 1TB drive shows up as 931GB in Windows.

Decimal vs Binary: Where the Confusion Comes From

Storage manufacturers sell drives using decimal (base-10) units, where 1 kilobyte equals 1,000 bytes, 1 megabyte equals 1,000,000 bytes, and 1 gigabyte equals 1,000,000,000 bytes. Operating systems, however, often report storage in binary (base-2) units, where 1 kibibyte (KiB) equals 1,024 bytes, 1 mebibyte (MiB) equals 1,048,576 bytes, and 1 gibibyte (GiB) equals 1,073,741,824 bytes. Windows labels these binary units as KB, MB, and GB even though it is technically using KiB, MiB, and GiB math, which is the entire source of the "missing storage" confusion people run into after buying a new drive.

The Real Math Behind a 1TB Drive Showing 931GB

A drive marketed as 1TB contains 1,000,000,000,000 bytes using the manufacturer's decimal definition. Windows reports storage using binary GiB, so it divides that byte count by 1,073,741,824 (bytes per GiB) instead of 1,000,000,000. The result: 1,000,000,000,000 / 1,073,741,824 = 931.32, which Windows displays as roughly 931GB. Nothing is missing or defective, it is purely a labeling mismatch between the two counting systems, and the same math explains why a 500GB drive shows as 465GB and a 256GB SSD shows as 238GB.

The Full Unit Ladder

Sizing Real Files and Transfers

A typical MP3 song at 128kbps runs about 3.5-4.5MB for a 4-minute track. A high-resolution smartphone photo from a modern 48-megapixel camera is often 8-15MB, depending on compression. An hour of 1080p video at a moderate bitrate lands around 1.5-3GB, while the same hour in 4K can hit 7-10GB or more. If you are transferring a 20GB folder over a home Wi-Fi connection rated at 100 megabits per second (Mbps), remember that network speeds are measured in bits, not bytes: 100Mbps equals 12.5MB per second, so 20GB (20,000MB) would take roughly 1,600 seconds, or about 27 minutes, under ideal conditions with no overhead.

Bits vs Bytes: The Other Common Mixup

Internet plans and network speeds are almost always advertised in bits per second (Mbps or Gbps), while file sizes and storage are measured in bytes (MB, GB). To convert, divide the bit rate by 8. A "500 Mbps" internet plan gives you a theoretical maximum download speed of 62.5 megabytes per second, not 500. This single division by 8 explains a huge share of "why is my download so slow" confusion, since people expect their file transfer speed in MB/s to match the number printed on their internet bill in Mbps.

How Much Storage Common Tasks Actually Use

• A basic text document: a few KB.
• A compressed PDF report with images: 1-5MB.
• A mobile app install: commonly 50-500MB.
• A modern AAA video game: 40-150GB, sometimes larger with day-one patches.
• A full smartphone camera roll after two years of regular use: often 30-80GB.

Convert Storage Units Instantly

Our free data storage converter handles bytes, KB, MB, GB, and TB in both decimal and binary conventions, so you can see exactly why your drive, download, or backup size looks different depending on where the number came from.