Mbps Calculator
Convert Mbps to MB/s and other data rates, and see how long a download actually takes.
Download times at this speed
| File | Time |
|---|---|
| Photo (5 MB) | 0:00 |
| Album (100 MB) | 0:08 |
| HD film (5 GB) | 6:40 |
| 4K film (25 GB) | 33:20 |
| Game (80 GB) | 1:46:40 |
| Disk image (1 TB) | 22:13:20 |
Bits and bytes: the factor of eight
Internet speeds are sold in bits per second; file sizes are in bytes. There are 8 bits in a byte, so:
MB/s = Mbps ÷ 8
A 100 Mbps connection downloads at about 12.5 MB/s at best. That is not your provider under-delivering — it is the unit changing. The capital B in MB/s means bytes; the lower-case b in Mbps means bits.
Why real downloads are slower
The theoretical figure ignores everything the network actually does. TCP/IP headers, acknowledgements, retransmissions, encryption and Wi-Fi contention all consume capacity — typically 5-10% on a wired connection and considerably more over Wi-Fi or a congested link. The overhead field lets you model that; set it to zero for the marketing number.
The server at the other end and your own disk can also be the bottleneck. A gigabit connection can outrun a slow hard drive.
Decimal or binary?
Network rates use strict decimal powers: 1 Mbps is exactly 1,000,000 bits per second. Storage is sold the same way, so this calculator uses decimal throughout. Operating systems, though, often report file sizes in binary units while labelling them MB or GB — which is why a “1 TB” drive shows as about 931 GB in Windows. That is a labelling difference, not missing space.