Mbps, MBps and GB: Understanding Internet Speed
Clear up the difference between bits and bytes so connection speeds and file sizes make more sense.
In this guide
The capital B matters
Mbps means megabits per second. MBps means megabytes per second. Since one byte contains eight bits, a 100 Mbps connection has a theoretical maximum of about 12.5 MBps before overhead and other losses.
Why downloads take longer than the simple maths
The headline speed is not the whole story. Wi-Fi quality, congestion, server capacity, routing and protocol overhead can all reduce the speed available to the actual file transfer.
Use the right units in planning
If a backup is 20 GB and your connection is measured in Mbps, convert the file size to bits before estimating the transfer time. Mixing GB and Mbps directly is a unit error.
Treat the result as an estimate
Transfer-time calculators are best for planning. If a transfer is important, allow some extra time rather than scheduling it to finish at the exact theoretical second.
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 →