File Size Converter — SI Decimal & 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
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.
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.
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.