File Size Converter

Convert file sizes between bytes, KB, MB, GB, TB, KiB, MiB and GiB

What is it and how does it work?

A file size converter changes a digital size between units — bytes, kilobytes, megabytes, gigabytes and terabytes — and crucially distinguishes the two systems that use those names. There are decimal units (KB, MB, GB) based on powers of 1000, and binary units (KiB, MiB, GiB) based on powers of 1024. Both are everywhere, and the mismatch between them is exactly why a "500 GB" drive shows up as roughly 465 GB in your operating system: the manufacturer counts in 1000s, the OS often counts in 1024s.

This tool lets you convert cleanly within either system, or compare across them, so you can answer questions like how many megabytes a file of so many bytes is, or why a download size and the space it takes on disk do not match. The 1000-versus-1024 distinction trips up almost everyone, and seeing both values side by side makes the discrepancy obvious rather than mysterious. Everything is calculated in your browser for an instant, exact result.

Common use cases

• Reading a file size: convert a size in bytes from a log or API into readable megabytes or gigabytes.
• Explaining a storage gap: see why a "1 TB" drive reports less usable space by comparing decimal and binary units.
• Planning capacity: work out how many files of a given size fit into an amount of storage.

Frequently asked questions

What is the difference between KB and KiB?

A kilobyte (KB) is 1000 bytes in the decimal system, while a kibibyte (KiB) is 1024 bytes in the binary system. The same naming idea extends up: MB vs MiB, GB vs GiB. They are close but not equal, and the gap grows with each step up.

Why does my hard drive show less space than advertised?

Drive makers measure capacity in decimal units (1 GB = 1,000,000,000 bytes), while many operating systems display in binary units (1 GiB = 1,073,741,824 bytes) but label it "GB". The bytes are the same; the unit definition differs, so a 500 GB drive reads as about 465 in the OS.

Which system should I use?

It depends on context. Storage marketing and network speeds usually use decimal (1000-based) units, while memory and many operating systems use binary (1024-based) units. When precision matters, state whether you mean KB or KiB to avoid the ambiguity entirely.

How many bytes are in a megabyte?

In the decimal system, 1 MB = 1,000,000 bytes. In the binary system, 1 MiB = 1,048,576 bytes (1024 × 1024). The roughly 5% difference per step is why large sizes can look noticeably different depending on which unit is meant.

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