What is a mebibyte (MiB)?

A mebibyte is exactly 1,048,576 bytes (2²⁰). The name comes from "mebi" (binary mega), defined by IEC 80000-13 to remove ambiguity between decimal megabytes (1,000,000 bytes) and binary megabytes (1,048,576 bytes). Most operating systems and memory specifications use the 1,048,576-byte definition.

What is the difference between MB and MiB?

1 MB (megabyte, SI/decimal) = 1,000,000 bytes. 1 MiB (mebibyte, IEC binary) = 1,048,576 bytes. The difference is roughly 4.86%. Storage manufacturers use MB with SI values; operating systems traditionally use the same labels but with binary (1,048,576) values. The IEC introduced MiB so the binary unit has an unambiguous name.

How do I convert bytes to mebibytes?

Divide the byte count by 1,048,576. For example, 10,485,760 bytes ÷ 1,048,576 = 10 MiB. For non-power-of-two values, the result will be a decimal number.

Why does my OS show a drive as smaller than the box says?

Drive manufacturers label capacity in decimal (1 GB = 1,000,000,000 bytes). Your OS reports in binary (1 GiB = 1,073,741,824 bytes), so the same drive appears smaller. No data is missing — it is a units difference, not data loss.

Is this converter exact?

Yes. Since 1 MiB is defined as exactly 1,048,576 bytes, division is exact for integer byte counts. Fractional results use JavaScript 64-bit floating-point arithmetic, which is accurate to 15–16 significant digits.

Bytes to Mebibytes Converter

Enter a byte value and instantly see the equivalent in mebibytes (MiB) using the IEC binary standard where 1 MiB = 1,048,576 bytes exactly.

Enter Bytes

Bytes (B)

MB vs MiB — what is the difference?

1 MB (megabyte, decimal) = 1,000,000 bytes

1 MiB (mebibyte, binary) = 1,048,576 bytes

IEC 80000-13 introduced "MiB" to give the binary unit (2²⁰ bytes) an unambiguous name separate from the decimal megabyte.

Result

Enter a byte value and click Convert.

Common Byte to MiB Reference

Bytes	MiB (÷ 1,048,576)	MB (÷ 1,000,000)	Common size

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Summary

A mebibyte (MiB) is exactly 1,048,576 bytes — a binary unit defined by IEC 80000-13 as 2²⁰ bytes. This is distinct from a megabyte (MB), which manufacturers define as 1,000,000 bytes under the SI decimal system. The difference is about 4.86%: a file your OS labels "512 MB" often means 512 MiB (536,870,912 bytes), not 512,000,000 bytes. This tool converts any byte count to MiB with full precision, and shows the megabyte equivalent for side-by-side comparison.

How it works

Enter any number of bytes in the input field.
The converter divides by 1,048,576 (2²⁰) to produce the mebibyte value per the IEC 80000-13 binary standard.
A secondary result shows megabytes (MB) using the SI decimal standard (÷ 1,000,000) for comparison.
The calculation steps panel shows the exact formula applied.
The reference table lists common byte counts alongside their exact MiB equivalents.

Use cases

Convert RAM or memory buffer sizes from bytes to MiB for system documentation.
Understand why a "256 MB" flash chip holds fewer bytes than an OS reports in MiB.
Translate file sizes from bytes to MiB for IEC-standard technical specifications.
Check the exact MiB value of a disk partition size reported in bytes.
Clarify the MB vs MiB distinction in kernel configuration or storage engineering.

Frequently Asked Questions

Last updated: 2026-06-19 · Reviewed by Nham Vu