File Size Calculator
Convert between file size units (B, KB, MB, GB, TB, PB) with binary and decimal modes. Calculate total storage needs and estimate download times.
File Size Converter
Multi-File Storage Calculator
Calculate the total storage needed for multiple files.
Download Time Calculator
Calculate how long it takes to download a file at a given bandwidth.
Binary & Decimal
Support for both IEC (1024) and SI (1000) standards.
Multi-File Totals
Calculate total storage for multiple files at once.
Download Time
Estimate download times based on bandwidth.
Frequently Asked Questions
What is the difference between binary and decimal file sizes?
Binary (IEC) uses base 1024, where 1 KiB = 1024 bytes. This is commonly used by operating systems. Decimal (SI) uses base 1000, where 1 KB = 1000 bytes. This is commonly used by storage manufacturers. For example, 1 GiB = 1,073,741,824 bytes while 1 GB = 1,000,000,000 bytes.
How do I convert GB to MB?
In binary mode: 1 GB = 1024 MB. In decimal mode: 1 GB = 1000 MB. Simply enter your value, select GB as the "from" unit and MB as the "to" unit, then click Convert.
How is download time calculated?
Download time is calculated by converting your file size to megabytes, then dividing by your bandwidth in MB/s (which is your bandwidth in Mbps divided by 8). For example, a 1000 MB file on a 100 Mbps connection takes approximately 80 seconds.
Why do hard drives show less space than advertised?
Manufacturers use decimal (SI) units where 1 TB = 1000 GB, but operating systems use binary (IEC) units where 1 TiB = 1024 GiB. A 1 TB drive actually has about 931 GiB of usable space when viewed in your operating system.
What units are supported?
This calculator supports B (Bytes), KB/KiB (Kilobytes), MB/MiB (Megabytes), GB/GiB (Gigabytes), TB/TiB (Terabytes), and PB/PiB (Petabytes) in both binary and decimal modes.
Is this calculator free to use?
Yes! This file size calculator is 100% free with no sign-up required. All calculations happen in your browser for complete privacy.