Mbps vs MB/s
Lower-case b is bits, upper-case B is bytes. Divide Mbps by 8 for MB/s: 50 Mbps ≈ 6.25 MB/s, 500 Mbps ≈ 62.5 MB/s, 1 Gbps ≈ 125 MB/s. Browsers and download managers show MB/s; your plan and speed tests show Mbps.
Why real downloads are slower
- Protocol overhead takes a few percent, so the calculator also shows 80% of full speed.
- The server may be slower than your connection, especially for big files from busy sites.
- Wi-Fi signal, other devices on the network and VPNs all take a share.
Measure your real speed
macOS 12 and later include a speed test in Terminal. Drippy shows live download and upload speeds in the menu bar, so you can see what a download is actually getting while it runs.
networkQualityQuestions
How long does it take to download 1 GB at 100 Mbps?
About 80 seconds at full speed, closer to 100 seconds in practice.
Is 100 Mbps the same as 100 MB/s?
No. 100 Mbps is 12.5 MB/s. Divide megabits by 8 to get megabytes.
Why does my download show a lower speed than my speed test?
The server you're downloading from, Wi-Fi and other traffic all limit it. A speed test uses servers chosen to be fast and close.