What is the difference between MB and MiB?

A megabyte (MB) is a decimal unit equal to 1,000,000 bytes, while a mebibyte (MiB) is a binary unit equal to 1,048,576 bytes (1024 × 1024). Storage vendors advertise in decimal MB/GB/TB, while many operating systems report binary MiB/GiB but often label them MB/GB — which is why a 1 TB drive appears as about 931 GiB.

Are these conversions accurate?

Yes. The converter uses the exact factors 1 KB = 1000 bytes (decimal) and 1 KiB = 1024 bytes (binary), and shows both systems plus the raw byte count to 6 decimal places.

Is my data sent anywhere?

No. The converter is privacy-first and runs entirely in your browser — the value you type never leaves your device.

Why does my 1 TB hard drive show as 931 GB?

The manufacturer counts 1 TB as a decimal trillion bytes (1,000,000,000,000), but your operating system divides by 1024 three times to report binary gibibytes, which it usually labels GB. 1,000,000,000,000 ÷ 1024³ ≈ 931, so the same drive looks smaller even though no space is missing.

Should I use decimal or binary units?

Use decimal (KB, MB, GB) for storage and bandwidth marketing figures, and binary (KiB, MiB, GiB) when you need the values your OS or RAM actually uses. This tool shows both so you never have to guess which a figure refers to.

File Size Converter — Gera Tools

File Size Converter

File sizes are quoted in two competing systems — decimal (SI) and binary (IEC) — and the mismatch causes constant confusion, from “missing” hard-drive space to download estimates that look wrong. This converter takes one value and expresses it across bytes, KB, MB, GB, TB and PB (decimal) and the binary KiB, MiB, GiB, TiB and PiB (IEC) units at once, so you can compare a vendor’s figure with what your operating system reports.

How it works

The two systems differ only by their base. The decimal units step up by 1000 (1 KB = 1000 bytes), while the binary units step up by 1024 (1 KiB = 1024 bytes). The tool converts your input to a raw byte count, then divides by the correct power of 1000 or 1024 for every unit:

Decimal: 1 KB = 1000 bytes · Binary: 1 KiB = 1024 bytes (1024 = 2¹⁰)

Because storage vendors advertise in decimal but most operating systems count in binary (often mislabelling GiB as “GB”), the same file or drive can show two different numbers.

Example

A drive sold as 1 TB holds 1,000,000,000,000 bytes (decimal). Converting that byte count to binary gibibytes: 1,000,000,000,000 ÷ 1024³ ≈ 931.32 GiB — which is why your OS reports about 931 GB.

Decimal	Bytes	Binary equivalent
1 KB	1,000	0.9766 KiB
1 MB	1,000,000	0.9537 MiB
1 GB	1,000,000,000	0.9313 GiB
1 TB	1,000,000,000,000	931.32 GiB

Everything is calculated locally in your browser — nothing is sent anywhere.