Before building Bandwidth Calculator, we ran a real calculation — 700MB at 100Mbps — through an existing download-time calculator and watched what it did with the result.
It told us the number wasn't realistic. Then gave us the number anyway.
The result: "56.00 seconds" — a clean theoretical figure. Elsewhere on the very same page, a bandwidth-comparison chart carries the caption "Theoretical data transfer rates - not necessarily realistic values." The tool clearly knows the gap exists. It just doesn't apply that knowledge to its own headline number. In practice, protocol overhead, Wi-Fi loss, and network congestion routinely bring real-world throughput down to something like 70–80% of the theoretical figure — so this tool shows a realistic estimate (adjustable efficiency, default 80%) right next to the theoretical one, not as an afterthought.
Bits and bytes, spelled out every time
The bits-vs-bytes mix-up (Mbps vs MB/s — a factor of 8) is a well-documented, extremely common source of "why is my download so slow" confusion. This tool states the conversion explicitly under every result, instead of assuming you'll remember to divide by 8 yourself.
