What is the difference between MB and MiB?

MB (megabyte, SI) = 1,000 × 1,000 = 1,000,000 bytes. MiB (mebibyte, IEC) = 1,024 × 1,024 = 1,048,576 bytes. A 500 MB file is about 476.8 MiB. Windows reports sizes in MiB but labels them MB, which causes frequent confusion.

Why does a 1 TB hard drive show as less in Windows?

Hard drive manufacturers use SI decimal (1 TB = 1,000,000,000,000 bytes), but Windows reports in binary IEC units and labels them TB — so 1 TB (SI) appears as approximately 931 GiB in Windows Explorer.

How many bytes are in a gigabyte?

In SI/decimal: 1 GB = 1,000,000,000 bytes. In IEC/binary: 1 GiB = 1,073,741,824 bytes. For network speeds and storage specs, GB (decimal) is standard. For RAM and operating systems, GiB (binary) is used.

What units does this file size converter support?

ToolMint's File Size Converter supports 12 units: Bit, Byte, Kilobyte (KB), Megabyte (MB), Gigabyte (GB), Terabyte (TB), Petabyte (PB) and Kibibyte (KiB), Mebibyte (MiB), Gibibyte (GiB), Tebibyte (TiB), Pebibyte (PiB).

How large is a Blu-ray disc in GB and GiB?

A single-layer Blu-ray disc holds 25 GB (SI). In IEC units that is approximately 23.28 GiB. Dual-layer Blu-ray holds 50 GB ≈ 46.57 GiB. These values are shown in the Quick Reference cards.

File Size Converter – MB to GB, KB to MB, SI & IEC Binary Units

Convert between 12 file size units — bits, bytes, KB, MB, GB, TB, PB (SI decimal) and KiB, MiB, GiB, TiB, PiB (IEC binary). See both systems side by side, understand the MB vs MiB difference, and compare against real-world media sizes with built-in quick reference cards.

Enter File Size

Value

Unit

Included File Size Converter Tools

Decimal (SI) Units Converter

Convert using powers of 1,000 — KB, MB, GB, TB, PB — the standard used by hard drive manufacturers and file system tools on Windows.

Binary (IEC) Units Converter

Convert using powers of 1,024 — KiB, MiB, GiB, TiB, PiB — the standard used by RAM specs, Linux, and macOS Disk Utility.

Full Unit Input (12 Units)

Enter any value from bits to pebibytes. Both SI and IEC outputs update simultaneously so you can compare the two systems side by side.

Quick Reference Cards

See real-world size benchmarks — Floppy disk, CD, DVD, Blu-ray, USB drive, and SSD — in both SI and IEC formats at a glance.

Who Uses a File Size Converter

Understanding Storage Specs

Decode why your 1 TB hard drive shows less in Windows — hard drives use SI decimal, but Windows reports binary GiB labeled as GB.

Web & App Development

Convert file upload limits, API payload sizes, and bandwidth quotas between KB, MB, and GB to set correct thresholds in your code.

Cloud & Backup Planning

Calculate how much cloud storage you need by converting your data size from your OS's reported GiB to the provider's SI GB billing unit.

How to Convert File Sizes

Enter a value

Type the file size you want to convert into the input field.

Select the unit

Choose your source unit from the dropdown — from bits to pebibytes.

Read both outputs

The Decimal (SI) and Binary (IEC) sections both update instantly so you can see the difference between MB and MiB.

Check quick reference

Scroll to the Quick Reference section to compare your value against real-world storage media like CDs, Blu-rays, and SSDs.

The KB vs KiB Confusion – Why File Sizes Differ Between Devices

One of the most persistent sources of confusion in computing is that the same file can appear to be different sizes depending on which operating system, application, or device you use to view it. The root cause is that two competing standards define what "kilo", "mega", and "giga" mean for file sizes. In the SI (International System of Units) decimal standard, 1 KB = 1,000 bytes, 1 MB = 1,000,000 bytes, and 1 GB = 1,000,000,000 bytes. This is the standard used by hard drive manufacturers, network speed ratings, and most cloud storage providers — because it makes their numbers look larger. The IEC binary standard uses powers of 1,024 instead: 1 KiB = 1,024 bytes, 1 MiB = 1,048,576 bytes, 1 GiB = 1,073,741,824 bytes. Windows, Linux kernels, and RAM specifications use binary units — but Windows labels them as KB/MB/GB without the "i", which is technically incorrect per IEC 80000-13 but deeply ingrained. The practical consequence: a hard drive advertised as 1 TB (SI) will show as approximately 931 GB in Windows because Windows is actually reporting 931 GiB. The data is not missing — the units are just different.

KB, MB, GB, TB, PB – File Size Reference for Real-World Files

To make file size numbers meaningful, here is a practical reference guide. A plain text document is typically a few KB. A single high-quality JPEG photo from a modern smartphone is 3–8 MB. A 3-minute MP3 audio track at 128 kbps is about 3 MB; at 320 kbps, roughly 7 MB. A full HD (1080p) movie is typically 4–15 GB depending on codec and runtime. A 4K movie can be 50–100 GB uncompressed or 15–25 GB in H.265. Standard-definition video games are 1–10 GB; modern AAA titles regularly exceed 100 GB. A single-layer Blu-ray disc holds 25 GB (SI). A terabyte (1 TB) holds roughly 250,000 photos, 200 movies in HD, or 500 hours of video at 1080p. For developers: a typical npm node_modules folder is 200–500 MB; a full Docker image is 100 MB–2 GB depending on the base. Understanding these reference points makes it much easier to evaluate whether a file size is reasonable or something has gone wrong with a download, export, or compression step.

Frequently Asked Questions

What is the difference between MB and MiB?: MB (megabyte, SI) = 1,000 × 1,000 = 1,000,000 bytes. MiB (mebibyte, IEC) = 1,024 × 1,024 = 1,048,576 bytes. A 500 MB file is about 476.8 MiB. Windows reports sizes in MiB but labels them MB, which causes frequent confusion.
Why does a 1 TB hard drive show as less in Windows?: Hard drive manufacturers use SI decimal (1 TB = 1,000,000,000,000 bytes), but Windows reports in binary IEC units and labels them TB — so 1 TB (SI) appears as approximately 931 GiB in Windows Explorer.
How many bytes are in a gigabyte?: In SI/decimal: 1 GB = 1,000,000,000 bytes. In IEC/binary: 1 GiB = 1,073,741,824 bytes. For network speeds and storage specs, GB (decimal) is standard. For RAM and operating systems, GiB (binary) is used.
What units does this file size converter support?: ToolMint's File Size Converter supports 12 units: Bit, Byte, Kilobyte (KB), Megabyte (MB), Gigabyte (GB), Terabyte (TB), Petabyte (PB) and Kibibyte (KiB), Mebibyte (MiB), Gibibyte (GiB), Tebibyte (TiB), Pebibyte (PiB).
How large is a Blu-ray disc in GB and GiB?: A single-layer Blu-ray disc holds 25 GB (SI). In IEC units that is approximately 23.28 GiB. Dual-layer Blu-ray holds 50 GB ≈ 46.57 GiB. These values are shown in the Quick Reference cards.

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