File Size Converter
Convert MB to GB, bytes to KB, and all file size units free online. Supports both decimal (SI) and binary (IEC) standards. No signup needed.
How to Use File Size Converter
- 1Enter your file size value in the input field.
- 2Select the unit you are converting from (Bytes, KB, MB, GB, TB, etc.).
- 3Toggle between SI (decimal: 1 KB = 1,000 bytes) and IEC (binary: 1 KiB = 1,024 bytes).
- 4All equivalent sizes appear simultaneously in the conversion table.
- 5Click any row to copy that value to your clipboard.
About File Size Converter
Need to convert MB to GB online? Enter any file size and this free file size calculator shows the equivalent in every unit simultaneously — bytes, KB, MB, GB, TB, and PB — so you never need to calculate twice.
The tool supports both the decimal (SI) standard used in hard drive marketing (1 GB = 1,000 MB) and the binary (IEC) standard used by operating systems (1 GiB = 1,024 MiB). This is why a "1 TB" hard drive shows up as only ~931 GB in Windows — and this tool lets you check both calculations at once.
Toggle between SI and IEC standards with one click to see how the same storage amount is represented in each system. Useful for developers checking API payload sizes, IT professionals sizing storage systems, and anyone trying to understand why their storage shows less space than advertised.
All conversions update instantly. No account, no download, works on any device.
How File Size Converter Works
The File Size Converter converts between all standard digital storage units — bits, bytes, kilobytes, megabytes, gigabytes, terabytes, and petabytes — instantly. It supports both the SI (decimal) standard used by storage manufacturers and the IEC (binary) standard used by operating systems. In the SI system, 1 kilobyte = 1,000 bytes. In the binary IEC system, 1 kibibyte (KiB) = 1,024 bytes. This distinction explains why a 500 GB hard drive shows as ~465 GiB in Windows — the OS counts in binary while the manufacturer labels in decimal. Enter any value in any field and the tool recalculates all other units simultaneously.
SI (decimal): 1 KB = 10³ B, 1 MB = 10⁶ B, 1 GB = 10⁹ B, 1 TB = 10¹² B
IEC (binary): 1 KiB = 2¹⁰ B = 1,024 B, 1 MiB = 2²⁰ B, 1 GiB = 2³⁰ B, 1 TiB = 2⁴⁰ BReference Data
File Size Conversion Reference
| Unit | Symbol | Standard | Bytes |
|---|---|---|---|
| Bit | b | — | 0.125 |
| Byte | B | — | 1 |
| Kilobyte | KB | SI | 1,000 |
| Kibibyte | KiB | IEC | 1,024 |
| Megabyte | MB | SI | 1,000,000 |
| Mebibyte | MiB | IEC | 1,048,576 |
| Gigabyte | GB | SI | 1,000,000,000 |
| Gibibyte | GiB | IEC | 1,073,741,824 |
| Terabyte | TB | SI | 1,000,000,000,000 |
| Tebibyte | TiB | IEC | 1,099,511,627,776 |
Who Uses This Tool and Why
- ✓Developers specify API payload limits or upload size caps in consistent units, converting MB to bytes for code constants without manual calculation.
- ✓Network engineers convert file size to megabits online to estimate transfer times over connections rated in Mbps (e.g., a 500 MB file ÷ 100 Mbps = ~40 seconds).
- ✓Cloud storage administrators reconcile billing statements that use GB vs. GiB to understand the real cost per unit of storage.
- ✓Gamers and media consumers check whether a game download or video file will fit on their drive before committing to the download.
- ✓Database administrators calculate index sizes and table storage requirements before provisioning disk space for a new database.
Limitations & Practical Tips
Known Limitations
- •The tool converts between units but cannot tell you the actual file size of a specific file — you need to check file properties in your OS for that.
- •Bandwidth calculations require knowing both file size (in bits) and connection speed (in bits per second). Transfer time also depends on network overhead, not just raw throughput.
- •Storage capacity labelling conventions differ between manufacturers and OS vendors — always check whether your OS uses binary (GiB) reporting to avoid confusion.
Tips for Best Results
- →When calculating transfer time, convert file size to megabits (multiply MB by 8) and divide by your connection speed in Mbps for a quick estimate.
- →For precise cloud storage cost comparisons, always use the same unit — most cloud providers bill in GB (SI), not GiB.
- →Remember: 1 MB = 8 Megabits. Internet speeds are usually in Megabits per second (Mbps), while file sizes are in Megabytes (MB).
Frequently Asked Questions
- What is the difference between KB and KiB?
KB (kilobyte) = 1,000 bytes in the SI/decimal system used by storage manufacturers. KiB (kibibyte) = 1,024 bytes in the IEC binary system used by operating systems. A "500 GB" hard drive is 500,000,000,000 bytes, which Windows shows as ~465 GiB. This discrepancy is why your OS shows less space than the box says.
- Why does Windows show less storage than the drive label says?
Drive manufacturers use decimal units (1 GB = 1,000,000,000 bytes). Windows reports in binary units (1 GB = 1,073,741,824 bytes). A 1 TB drive contains 1,000,000,000,000 bytes, which Windows reports as ~931 GB (actually gibibytes). The physical storage is the same — only the display unit differs.
- How many bytes are in a gigabyte?
In the SI (decimal) system: 1 GB = 1,000,000,000 bytes (10⁹). In the IEC (binary) system: 1 GiB = 1,073,741,824 bytes (2³⁰). For a 4K video file labeled "2 GB", it is 2,000,000,000 bytes = 1.862 GiB as your operating system would show.
- What is the largest file size unit?
Beyond terabytes (TB/TiB): petabyte (PB, 10¹⁵ bytes), exabyte (EB, 10¹⁸), zettabyte (ZB, 10²¹), yottabyte (YB, 10²⁴). The total amount of data created globally per year is now measured in zettabytes. A single petabyte of text would take thousands of years to read.
- How do I convert MB to GB?
Divide by 1,000 for decimal units: 2,500 MB ÷ 1,000 = 2.5 GB. Divide by 1,024 for binary units: 2,500 MiB ÷ 1,024 = 2.44 GiB. Use this converter to get both values instantly and see the difference between the two systems.
- What file size units do internet speeds use?
Internet speeds are measured in bits per second (Mbps, Gbps), not bytes. To convert download speed to file download time: divide file size in megabits by speed in Mbps. A 100 MB file = 800 megabits; at 100 Mbps it takes about 8 seconds. Note: your ISP's "100 Mbps" plan means megabits, not megabytes.
- How big is a typical photo, video, or document?
Approximate file sizes: JPEG photo (12MP): 3–6 MB. RAW photo: 20–40 MB. 1 minute HD video (H.264): 150–500 MB. 1 minute 4K video: 500 MB–2 GB. MP3 song (3 min): 3–10 MB. PDF document (10 pages): 100 KB–5 MB. Word document: 50–500 KB.
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Last updated: May 2, 2026 — File Size Converter by CalcDash.