File Size Calculator
Calculate actual file sizes and convert between different units (Bytes, KB, MB, GB, TB) instantly and accurately with our free online tool.
Upload File
Select a file to calculate its actual size
Drop file here or click to browse
Any file type supported • Max size: No limit
Manual Calculation
Enter values to convert between units
Why Use Our File Size Calculator?
Powerful features designed for accuracy and ease of use
File Upload Analysis
Upload any file to get its exact size in all units instantly
Unit Conversion
Convert between bytes, KB, MB, GB, TB, and PB with precision
100% Private
All calculations happen locally in your browser - no uploads
Instant Results
Get immediate calculations with no waiting time or delays
How to Use
Simple steps to calculate and convert file sizes
Choose Method
Select either file upload for actual size calculation or manual input for unit conversion
Upload or Enter
Either drag & drop a file or enter a numeric value with the appropriate unit
Get Results
View instant results showing the file size in all common units (B, KB, MB, GB, TB)
Example Conversions
See how different file sizes convert across units
Small File
Medium File
Large File
Where This Tool is Used
Professional applications across different industries
System Administration
- Planning server storage capacity
- Monitoring disk usage
- Calculating backup requirements
- Optimizing storage allocation
Web Development
- Optimizing website assets
- Calculating bandwidth usage
- Managing file upload limits
- Performance optimization
Media Production
- Estimating video file sizes
- Planning storage for projects
- Calculating transfer times
- Managing media libraries
Education & Learning
- Understanding digital storage
- Computer science education
- File management training
- Technical documentation
Frequently Asked Questions
Common questions about file size calculation and conversion
What is file size?
File size refers to the amount of storage space a file occupies on a storage device. It's measured in bytes and its multiples (KB, MB, GB, TB). The size depends on the file's content, format, and compression level.
How is file size calculated?
File size is calculated by counting the total number of bytes the file contains. Our tool reads the file's metadata to determine its exact size, then converts it to different units using standard conversion factors (1 KB = 1,024 bytes, 1 MB = 1,024 KB, etc.).
What's the difference between KB and MB?
KB (Kilobyte) = 1,024 bytes, while MB (Megabyte) = 1,024 KB = 1,048,576 bytes. So 1 MB is 1,024 times larger than 1 KB. This follows the binary system used in computing.
Is my file data secure when using this tool?
Yes, absolutely! This tool processes files entirely in your browser using JavaScript. Your files never leave your device or get uploaded to any server. We only read the file size information, not the content.
What file types are supported?
All file types are supported! Since we only read the file size metadata, the tool works with any file format including documents, images, videos, audio files, archives, executables, and more.
Why use binary (1024) instead of decimal (1000) conversion?
Computers use binary system, so storage is calculated in powers of 2. While some systems use decimal (1000), the binary system (1024) is more accurate for computer storage calculations and is the standard used by most operating systems.