How to Estimate File Transfer Time
Learn why a 100 Mbps connection does not transfer 100 MB every second, and how to estimate upload or download time.
In this guide
Bits and bytes are not the same
Internet connection speeds are commonly advertised in bits per second, such as Mbps. File sizes are often shown in bytes, such as MB or GB. There are eight bits in a byte, so the units need to be converted before doing the calculation.
The basic estimate
Convert the file size to bits, then divide by the connection speed in bits per second. The result is the theoretical transfer time. In real use, transfers are usually slower because of protocol overhead, Wi-Fi conditions, server speed and other traffic.
A practical example
A 1 GB file contains roughly 8 gigabits using decimal units. At a steady 100 Mbps, the simple theoretical calculation is about 80 seconds. Real-world time may be longer.
Why Wi-Fi can change the result
Your internet package may say 100 Mbps while the device is connected through a busy or weak Wi-Fi link. The slowest part of the path often determines the actual speed you experience.
Try the related tool
If you came here because you need to do the calculation or create something now, you can use the matching KingToolsKit tool and then come back to the guide when you want the explanation.
Open the tool →