Bandwidth Calculator
Calculate download times and bandwidth requirements. Convert between Mbps, MBps, and estimate transfer times for files.
Last reviewed by the Radiatus Cloud team
Estimated Transfer Time
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How long will this actually take to transfer?
Estimating a download or upload time is where the bits-versus-bytes confusion bites hardest. A file is measured in bytes, a connection in bits per second, and the factor of eight between them is why a "100 megabit" line does not move a hundred megabytes a second. This calculator takes a file size and a connection speed, in whichever units you have them, and gives the realistic transfer time.
The eight-times trap, handled for you
Mbps is megabits per second; MBps is megabytes per second; they differ by a factor of eight, and mixing them up produces answers that are wrong by that factor. The calculator keeps the units straight, converting between Kbps, Mbps, KB, MB, GB and TB so you compare like with like. That single conversion is the source of most "why is this so slow" surprises.
An estimate, and why reality is slower
The calculated time is a theoretical best case at the full line rate. Real transfers are slower because of protocol overhead, shared links, server limits and distance. Treat the figure as a floor: a transfer will take at least this long, usually somewhat more. The calculation runs in your browser.
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Frequently Asked Questions
Why is a 100 Mbps connection not 100 MB per second?
Because Mbps is megabits and MB is megabytes, which differ by a factor of eight. A 100 Mbps line moves about 12.5 megabytes per second at best.
What is the difference between Mbps and MBps?
Mbps is megabits per second, the usual way connection speeds are advertised; MBps is megabytes per second, the way file sizes relate. They differ by eight.
Why does my real transfer take longer than the estimate?
The estimate is the theoretical best case at full line rate. Protocol overhead, shared links, server limits and distance all make real transfers slower.
Which units can it convert between?
File sizes in KB, MB, GB and TB, and speeds in Kbps and Mbps, keeping bits and bytes straight so you compare like with like.
Is anything uploaded?
No. The calculation runs entirely in your browser.
Privacy & Security
Calculated locally in browser.
About This Tool
This tool runs entirely in your browser. No data is sent to any server, ensuring complete privacy. Simply use the interface above to get started — no registration or login required.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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