What is a File Size Converter?
A file size converter is a free online tool that instantly converts digital storage units including Bit, Byte, KB, MB, GB, TB, and PB. Simply enter a number and select a unit to get real-time conversions across all units. It uses decimal (1,000-based), matching manufacturers, macOS, and networks; the common question 'Why does my 1TB drive show as 931GB?' is answered automatically with a Windows (1,024-based) gap note for large capacities.
Key Features
7-Unit Real-Time Conversion
Converts Bit, Byte, KB, MB, GB, TB, and PB simultaneously. Click any result row to instantly switch the base unit.
Automatic real-capacity gap
Enter a large capacity like GB or TB and the tool automatically explains why a 1TB drive shows as 931GB — the gap between manufacturer (1,000) and Windows (1,024) counting.
Transfer Time Calculator
Automatically calculates transfer time for 6 connection types: 4G LTE, 5G, WiFi 6, USB 2.0/3.0, and Ethernet.
Storage Capacity Comparison
See how many MP3s, photos, FHD movies, 4K movies, or AAA games fit in the given size — at a glance.
Understanding File Size Units
| Unit | In Bytes | Common Use |
|---|---|---|
| 1 KB | 1,000 B | Text documents, icons |
| 1 MB | 1,000,000 B | MP3 music, high-res photos |
| 1 GB | 1,000,000,000 B | Movies, game installations |
| 1 TB | 1,000,000,000,000 B | Large backups, NAS storage |
| 1 PB | 1,000,000,000,000,000 B | Data centers, cloud storage |
* The default is decimal (manufacturer·macOS, 1KB = 1,000B). Windows Explorer uses binary (1KB = 1,024B = technically KiB), so the same capacity appears smaller.
How to Use File Size Converter
- Select Unit — Choose the file size unit from Bit, Byte, KB, MB, GB, TB, or PB.
- Enter Value — Type the number you want to convert. Use quick select buttons for common values.
- View Results — See automatic conversions to all units. Click any unit to change the base.
- Check real capacity — Enter a large capacity like GB or TB and a gap note such as 'Labeled 1TB = about 931GB in Windows' appears automatically, showing the manufacturer (decimal) vs Windows (binary) difference.
Use Cases
Cloud Storage Planning
Calculate storage capacity for Google Drive, iCloud, Dropbox, and other cloud services to track remaining space.
File Transfer Time
Estimate download/upload time based on file size and internet speed.
Web Optimization
Analyze image and script file sizes for web pages to optimize loading speed.
Server & Storage Management
Perform unit conversions for server disk planning, NAS storage configuration, and backup capacity estimation.
FAQ
Q. How many MB is 1GB?
It depends on the standard. In decimal (manufacturer·macOS), 1GB = 1,000MB; in binary (Windows), 1GB = 1,024MiB. It's the same capacity, just counted differently.
Q. How many GB is 1TB?
In decimal (manufacturer·macOS), 1TB = 1,000GB. Windows, however, displays 1TB (one trillion bytes) as about 931GB. Terabytes are common for large hard drives, SSDs, and cloud storage.
Q. The box says 1TB but my PC shows 931GB — why?
Manufacturers advertise 1TB as 1,000,000,000,000 bytes (decimal), but Windows divides by 1,024, showing about 931GB. Nothing is missing or defective — it's just a different way of counting capacity.
Q. What's the difference between KB and KiB?
KB (kilobyte) is 1,000 bytes, while KiB (kibibyte) is 1,024 bytes. This tool converts in decimal (1,000), matching manufacturers and macOS; the difference from Windows (1,024 · KiB) is shown as a gap note for large capacities.
Privacy Notice
This file size converter performs all calculations entirely within your browser. No data is sent to any server, and no information is stored or collected. Use with complete confidence.
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