How the storage transfer calculator works
Interface real-world rates
Spec sheets advertise God-mode numbers; real transfers deliver: USB 2.0 ~35 MB/s, USB 3.0 to a spinning drive ~110 (the drive, not the wire), to an SSD ~400, 1GbE NAS ~110, Thunderbolt/USB4 ~1,500. The bottleneck principle applies twice — the slower of interface AND drive governs.
The small-files penalty
Every file costs filesystem overhead: locate, open, write, close, update metadata. One 10 GB file streams at line rate; 10,000 one-megabyte files run 2–4× slower; 100,000 small files can run 5–10× slower. The fixes are structural: archive to one file, or accept the tax and let it run overnight.
Planning migrations
Drive migrations and backups that "should take an hour" take four when the file profile is ignored. The calculator prices the honest duration — and the scheduling insight follows: start small-file transfers before dinner, big-file transfers before coffee. Time estimates that respect the file profile are estimates you can trust.