File Size Converter
Convert between file size units instantly. Supports both binary (KiB, MiB, GiB) and decimal (KB, MB, GB) standards with a complete reference table for all units.
Unit System
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Conversion Details
Quick Reference — 1 Gibibyte (GiB) in All Binary Units
How It Works
The File Size Converter works by first converting your input value to bytes as a universal base unit, then converting from bytes to your target unit. The relationship between bits and bytes is fixed: 1 byte always equals 8 bits.
The key difference between binary and decimal systems lies in the multiplier. Binary (IEC) units use powers of 1024: 1 KiB = 1024 bytes, 1 MiB = 1,048,576 bytes, and so on. Decimal (SI) units use powers of 1000: 1 KB = 1000 bytes, 1 MB = 1,000,000 bytes, etc.
Operating systems like Windows often report sizes in binary units but label them with decimal prefixes (showing "GB" when they mean "GiB"), which is why a drive advertised as 500 GB appears as roughly 465 GB in Windows. macOS since 2009 uses true decimal units, so sizes match more closely with advertised capacity.
The IEC introduced distinct binary prefixes (KiB, MiB, GiB) in 1998 specifically to eliminate this confusion, though adoption has been gradual across the industry.
Frequently Asked Questions
KB (kilobyte) uses the decimal standard where 1 KB = 1000 bytes. KiB (kibibyte) uses the binary standard where 1 KiB = 1024 bytes. The difference grows larger with bigger units: 1 GB = 1,000,000,000 bytes while 1 GiB = 1,073,741,824 bytes, a difference of about 7.4%. The IEC introduced the binary prefixes (KiB, MiB, GiB) in 1998 to eliminate ambiguity.
Drive manufacturers use decimal units (1 GB = 1,000,000,000 bytes) to measure capacity, but Windows reports sizes in binary units while labeling them as GB. So a 500 GB drive (500,000,000,000 bytes) shows as approximately 465 "GB" in Windows because it is actually dividing by 1,073,741,824 (the binary gigabyte). The data is all there — the discrepancy is purely a labeling issue.
One byte always contains exactly 8 bits. This is a fixed relationship that applies regardless of whether you use binary or decimal unit systems. A bit (binary digit) is the smallest unit of data, representing a 0 or 1. A byte is the standard grouping of 8 bits and is the fundamental addressable unit in most computer architectures.
Binary units (KiB, MiB, GiB) are appropriate when discussing RAM, cache sizes, and operating system file sizes, as these systems allocate memory in powers of two. Decimal units (KB, MB, GB) are standard for storage manufacturer specifications, network bandwidth, and data transfer rates. In general, use binary when talking about computer memory and decimal when talking about storage capacity or network speeds.
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