How many bytes are in a megabyte?

In the SI decimal standard used by storage manufacturers, 1 MB = 1,000,000 bytes (10^6). In the IEC binary standard used by most operating systems, 1 MiB = 1,048,576 bytes (2^20). The gap between the two is about 4.9%.

Why does my OS show a different byte count than the manufacturer?

Manufacturers label sizes using SI (powers of 1000), so 1 MB = 1,000,000 bytes on the box. Windows historically used binary units (powers of 1024) but called them "MB." A 1 MB (SI) file therefore appears as roughly 0.954 MiB — or about 1,000,000 bytes either way — but the labeled number differs.

When should I use MB versus MiB?

Use MB (SI) for disk capacity, network speeds, and anything labeled by hardware or ISP specs. Use MiB (binary) when working with RAM, OS file-system reports, or any context where the system uses powers of 1024.

Is 1 MB = 1024 KB or 1000 KB?

Under SI: 1 MB = 1000 KB = 1,000,000 bytes. Under IEC binary: 1 MiB = 1024 KiB = 1,048,576 bytes. Both are correct — they apply to different contexts.

How accurate is this converter for fractional megabyte values?

Calculations use JavaScript 64-bit floating-point arithmetic, accurate to about 15–16 significant digits. For any practical file size, including sub-megabyte fractions, the precision is more than sufficient.

Megabytes to Bytes Converter

Enter a megabyte value and instantly see the equivalent in bytes (B), kilobytes (KB), and gigabytes (GB) for both SI and binary standards.

Enter Megabytes

Number of megabytes

Input unit

MB (SI): 1 MB = 1,000,000 bytes — used by storage manufacturers, ISPs, file transfers.

MiB (binary): 1 MiB = 1,048,576 bytes — used by OS file explorers and RAM specs.

Results

Enter a megabyte value and click Convert.

Common Megabyte Reference

Description	MB (SI)	Bytes	MiB (Binary)
Average JPEG photo	3 MB	3,000,000	2.861 MiB
MP3 song (~3 min)	5 MB	5,000,000	4.768 MiB
1 MiB (binary)	1.048576 MB	1,048,576	1 MiB
HD video (1 min, 720p)	100 MB	100,000,000	95.367 MiB
Typical app install	500 MB	500,000,000	476.837 MiB
1 GB (SI) = 1000 MB	1,000 MB	1,000,000,000	953.674 MiB

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Summary

Enter a megabyte value and instantly see the equivalent in bytes (B), kilobytes (KB), and gigabytes (GB) for both SI and binary standards.

How it works

Enter any number of megabytes (or mebibytes) in the input field.
Select whether your value is in MB (SI decimal) or MiB (binary IEC).
For MB: the converter multiplies by 1,000,000 to get bytes.
For MiB: the converter multiplies by 1,048,576 to get bytes.
All related SI and binary units (KB, KiB, GB, GiB) are shown alongside.
Use the copy button next to any result to grab the exact value.

Use cases

Verify how many bytes a file will occupy on disk given its megabyte listing.
Convert MB to bytes for API request-size limits that require a raw byte count.
Check if a file fits within a byte-level upload quota after being listed in MB.
Translate OS-reported MiB sizes to bytes for logging or database storage.
Calculate memory buffer sizes in bytes when documentation specifies megabytes.
Cross-check advertised storage (SI MB) with OS display (binary MiB) byte counts.

Frequently Asked Questions

Last updated: 2026-09-19 · Reviewed by Nham Vu