Data Size Converter
Convert between decimal and binary data units, and work out how long a transfer takes at a given link speed.
Transfer time
Network gear is rated in bits, disks in bytes.
Framing and protocol overhead never leaves you the full rate.
Bits, bytes and the missing gigabyte
A 1 Gbit/s link moves 125 MB per second at line rate, because there are eight bits in a byte. Subtract Ethernet, IP and TCP framing and you land near 117 MB/s on a clean link, which is the 94 percent figure above. Anything involving many small files, high latency, or SMB signing will be well below that.
The unit gap is the other half. Storage is sold in decimal units and reported by most operating systems in binary ones, so a 500 GB disk shows up as 465 GiB. macOS reports decimal and calls it GB, Windows reports binary and also calls it GB, which is the root of most of the confusion.