Bytes, bits and realistic transfer times

Distinguish decimal and binary prefixes

GB commonly denotes 10⁹ bytes, while GiB denotes 2³⁰ bytes. Both can describe the same quantity with different numerical values. A lowercase b in a rate denotes bits, while uppercase B denotes bytes. UnitTidy keeps these choices explicit. Select the definition printed by the source rather than assuming every product uses the same label.

Calculate an ideal lower bound

A 1 GB decimal file contains eight billion bits. At a sustained 100 Mbit/s, dividing bits by bits per second gives 80 seconds. This assumes the entire advertised rate carries file payload without delays. If the file is 1 GiB instead, the ideal duration is about 85.9 seconds. The difference comes from the size definition, not a slower network.

1 GB = 1,000,000,000 bytes
1 byte = 8 bits
8,000,000,000 / 100,000,000 = 80 seconds

Add the limits of the real path

Protocol overhead, shared Wi-Fi, packet loss, server limits and disk performance can make a transfer take longer. A speed test does not guarantee the same rate to every destination. Use the converter for unit consistency, then measure a representative real transfer to estimate your workflow. For a deadline, leave margin instead of promising completion at the theoretical minimum. Check whether an application reports a current rate, an average rate or a peak.