Units
Mbps vs MB/s: why your download looks eight times slower
Short answer: Mbps is megabits per second and MB/s is megabytes per second. One byte is eight bits, so divide a plan speed in Mbps by 8 to get the MB/s a download manager shows. A 500 Mbps plan peaks near 62.5 MB/s before any protocol overhead.
The two units
Internet plans and speed tests use bits per second; file sizes, browsers and game launchers mostly use bytes. The lowercase b is a bit and the uppercase B is a byte. Wikipedia's article on the byte notes that the de facto standard is eight bits, codified in IEC 80000-13, and that network documents such as RFC 791 use the word "octet" to mean exactly eight bits (Byte). That is why the factor is 8.
Conversion table
| Plan speed | Theoretical MB/s | Time for a 10 GB file |
|---|---|---|
| 25 Mbps | 3.12 MB/s | 53.3 min |
| 100 Mbps | 12.50 MB/s | 13.3 min |
| 300 Mbps | 37.50 MB/s | 4.4 min |
| 500 Mbps | 62.50 MB/s | 2.7 min |
| 940 Mbps | 117.50 MB/s | 1.4 min |
10 GB is counted here as 80,000 megabits (10 × 1,000 MB × 8). Times are the pure arithmetic of size ÷ speed; real downloads are slower because of packet overhead (see why gigabit tests at 940) and the server's own limits.
Worked example
You pay for 300 Mbps and Steam shows 36 MB/s. Divide 300 by 8: 37.5 MB/s is the ceiling, so 36 MB/s is 96% of it and the connection is working. If Steam showed 5 MB/s, that is 40 Mbps, and the cause is worth investigating with a speed test and the slow-internet checklist.
GB versus GiB
Some operating systems and tools report sizes in binary units where 1 GiB = 1,073,741,824 bytes, while storage makers and network speeds use decimal units. A 10 GiB file is therefore 85,899 megabits, about 7.4% more than the 80,000 megabits of 10 GB, so a download estimate based on the wrong unit can be off by that much. The download time calculator uses decimal units.
Quick rules
- Plan speed ÷ 8 = best-case MB/s.
- MB/s × 8 = Mbps.
- Upload speeds convert the same way; see download vs upload.
- Wi-Fi results are lower still: why results change.
Related
Mbps to MB/s converter · Download time calculator · Gigabit at 940 · Ethernet stuck at 100 · All guides