Technology

Because real systems rarely hit their headline numbers. A gigabit link does not transfer a gigabit of file data per second once protocol overhead, disk speed and contention are accounted for; a drive rated at 4 TB formats to roughly 3.64 TiB. Each tool states the overhead assumption it applies, and most let you override it with a figure you have measured yourself.

A measured result, taken at the busiest realistic time. Advertised speeds are usually described as an average available to a proportion of customers at peak, which is not the same as the throughput you will see on a particular device over Wi-Fi. Where a tool asks for a transfer rate, measure it once and reuse that figure.

Yes, and the distinction is stated wherever it changes the answer. Manufacturers use decimal units — a terabyte is 10¹² bytes — while operating systems generally report binary units, so a 4 TB disk shows as about 3.64 TB in Windows. Storage and backup tools show which convention they are using.

No. Every calculator here runs in your browser using JavaScript. That includes the password strength checker, which evaluates length and character variety locally and never transmits the password. Nothing is retained as a calculator record.

For sizing and sanity-checking, yes — the arithmetic is the same. For anything being procured, installed or relied on commercially, treat the output as a first pass. A Wi-Fi design should still be validated by a survey, and rack power and UPS sizing should be confirmed against manufacturer data and a qualified electrician.

Default values such as codec bitrates, typical drive sizes and RAID rebuild behaviour are reviewed alongside the rest of the section. Because hardware moves quickly, every default is editable rather than fixed, so a tool stays useful even when its supplied figure is no longer typical.