The confusion between Mbps and MB/s is common. It explains why a 1 Gbps plan does not download a file at 1,000 MB/s. The two units do not measure the same thing.
Bit and byte: the basics
A bit is the smallest unit of information. A byte equals 8 bits. Network speeds are usually expressed in bits per second, while file sizes are expressed in bytes.
Mbps, Mb/s, MB/s: the right units
| Unit | Meaning | Typical use |
|---|---|---|
| Mbps or Mb/s | Megabits per second | Internet speed |
| MB/s | Megabytes per second | File downloads |
| Gbps or Gb/s | Gigabits per second | Fiber plans |
| GB | Gigabytes | File size or data plans |
How to convert Mbps to MB/s
Divide the speed in Mbps by 8 to get MB/s. Example: 100 Mbps ÷ 8 = 12.5 MB/s. Conversely, multiply MB/s by 8 to get Mbps.
| Advertised speed | Theoretical download |
|---|---|
| 8 Mbps | 1 MB/s |
| 100 Mbps | 12.5 MB/s |
| 500 Mbps | 62.5 MB/s |
| 1 Gbps (1,000 Mbps) | 125 MB/s |
| 2 Gbps | 250 MB/s |
These values are theoretical. Network protocols, the server and the disk add overhead: expect 10–20% less in practice.
Why do ISPs use Mbps?
Network speeds have historically been measured in bits per second. It is also a more impressive unit: 1,000 Mbps looks bigger than 125 MB/s, even though they are equivalent.
How to compare a plan with a real download
If your software shows 10 MB/s, your speed is about 80 Mbps. If your plan advertises 500 Mbps, a 10 MB/s download is far below its potential. Check the server, cable and Wi-Fi before concluding there is a line problem.
Tip: to estimate download time, divide the file size in MB by the speed in MB/s. A 1 GB file (1,000 MB) at 12.5 MB/s takes about 80 seconds.
Frequently asked questions
How many MB/s is 1 Gbps?
1 Gbps equals 1,000 Mbps, or about 125 MB/s in theory. In practice, expect 100 to 115 MB/s depending on the server and hardware.
Why is my download slower than my speed?
The server, disk, Wi-Fi, cable or network load can limit the download. The advertised speed is a theoretical maximum.
What is the difference between GB and Gb?
GB means gigabyte (file size), while Gb means gigabit (speed). One GB equals 8 Gb.
Are Mbps and MB/s equivalent?
No, one byte equals 8 bits. To convert Mbps to MB/s, divide by 8.
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