Data Storage Converter

Data storage is the unit with the messiest marketing history. A '1 TB' hard drive shows up as 931 GB in your OS — because drive manufacturers use decimal (1 TB = 10¹² bytes) while operating systems often report binary (1 TiB = 2⁴⁰ bytes). That 7% gap is real, not a defect. This calculator supports both conventions so you can match whatever number you're comparing.

Computers work in binary — groups of 1024 (2¹⁰) bytes are natural because memory addresses are powers of 2. Storage manufacturers, since the 1990s, use decimal (1 KB = 1,000 bytes) because it makes the numbers on the box bigger and follows the SI prefix standard. IEC standardized the binary-specific prefixes in 1998: KiB, MiB, GiB, TiB (pronounced 'kibi,' 'mebi,' 'gibi,' 'tebi'). These are unambiguous — 1 KiB is exactly 1,024 bytes — but consumer software still often says 'KB' when it means KiB.

The 'byte' is 8 bits because that's enough to encode a character in ASCII (128 codes, needing 7 bits, padded to 8 for alignment). Networking speeds (Mbps, Gbps) are in bits per second; file sizes (MB, GB) are in bytes. A 100 Mbps connection transfers ~12.5 MB/sec, not 100. That factor-of-8 catches people.

MB to MiB: divide by 1.049 (MiB is 4.9% larger). GB to GiB: divide by 1.074. TB to TiB: divide by 1.1. The gap widens at each level because (1000/1024)ⁿ drifts with n.

For network speeds: bits per second ÷ 8 = bytes per second. A 1 Gbps home fiber line delivers max ~125 MB/sec. A 100 Mbps cable line delivers ~12.5 MB/sec. A 4G LTE connection (100 Mbps peak) delivers ~12.5 MB/sec at best. Real-world speeds are usually 50-80% of peak.

• Bytes
• Kilobytes (KB)
• Megabytes (MB)
• Gigabytes (GB)
• Terabytes (TB)
• Kibibytes (KiB)
• Mebibytes (MiB)
• Gibibytes (GiB)
• Bits

• Bytes vs bits. 'Mbps' is megabits per second; 'MBps' is megabytes per second. A difference of 8×. ISPs advertise in Mbps because the number is bigger.
• Decimal vs binary. A '4 TB drive' is 4,000,000,000,000 bytes = 3.64 TiB. Your OS reports 3.64 TB (really TiB). You didn't lose 9% of your drive; the labels just disagree.
• Kilo vs Kibi. 1 KB (decimal) = 1,000 bytes. 1 KiB (binary) = 1,024 bytes. Most software mislabels the second as 'KB.' Windows File Explorer reports binary; Mac Finder reports decimal since macOS 10.6.
• File size vs disk-used. A 1-byte file can use 4 KB on disk because of filesystem block allocation. Small files scale poorly.
• 'GB' in phone plans. Cellular carriers use decimal GB (1 GB = 10⁹ bytes), which is why your 'unlimited 5 GB' feels like it runs out faster than you expect.

• 1 page of text: ~5 KB (binary).
• 1 MP3 (3 min, 256 kbps): ~5.8 MB.
• 1 JPEG from a phone: 2-5 MB.
• 1 RAW photo from a mirrorless camera: 40-80 MB.
• 1 hour 4K video (60 fps, high bitrate): ~22 GB.
• 1 hour HD streaming (Netflix): ~3 GB.
• A Blu-ray disc holds 25 GB single-layer, 50 GB dual-layer.
• A 1 TB SSD actually holds 1,000,000,000,000 bytes = 931 GiB of user-addressable storage.
• A human brain is estimated to store 2.5 PB of 'data' (controversial; the brain isn't byte-addressable).
• Google's entire index (public estimate): ~100 PB of web documents.

• When buying a drive, subtract ~7% for usable space. A 4 TB drive gives you ~3.64 TiB usable.
• For network speed tests, divide the Mbps result by 8 to get MB/sec — the number that matters when estimating download times.
• Phone storage: OS and system files take 15-25 GB on a modern phone. A '128 GB' phone has about 100 GB of user storage.

Related: SI Prefix Converter · Time Converter · Frequency Converter.