Your internet plan says 300 Mbps, but your download shows 37 MB/s. Are you being shortchanged? Almost certainly not – you’re looking at two different units. This guide explains the difference between Mbps and MB/s, shows you how to convert between them in seconds, and helps you estimate how long a download should really take.
The short answer
- Mbps (megabits per second, small “b”) measures network speed. Internet providers and speed tests use it.
- MB/s (megabytes per second, capital “B”) measures file transfer speed. Browsers, Steam and download managers use it.
- 1 byte = 8 bits, so to convert Mbps to MB/s, divide by 8. A 300 Mbps connection downloads at about 37.5 MB/s.
Bits vs bytes
A bit is the smallest unit of digital data – a single 0 or 1. A byte is a group of 8 bits, enough to store one character of text. Networking has always been measured in bits, because data travels over cables and radio waves one bit at a time. Storage and files are measured in bytes, because that’s how computers organize data on disk.
The only visible difference in the abbreviation is the case of the letter “b”: lowercase b means bits, uppercase B means bytes. That tiny detail is responsible for a lot of confusion – and a lot of unnecessary calls to internet providers.
How to convert Mbps to MB/s
Divide by 8. Multiply by 8 to go the other way.
| Internet speed | Maximum download speed |
|---|---|
| 25 Mbps | 3.1 MB/s |
| 50 Mbps | 6.25 MB/s |
| 100 Mbps | 12.5 MB/s |
| 200 Mbps | 25 MB/s |
| 300 Mbps | 37.5 MB/s |
| 500 Mbps | 62.5 MB/s |
| 1 Gbps (1,000 Mbps) | 125 MB/s |
| 2 Gbps | 250 MB/s |
In practice, expect a download to run at roughly 90–95% of these numbers, because part of the connection is used by protocol overhead (the data that addresses and checks every packet).
How long will my download take?
To estimate download time, convert the file size to megabits and divide by your speed:
Time (seconds) = file size in MB × 8 ÷ speed in Mbps
For example, a 50 GB game (50,000 MB) on a 300 Mbps connection: 50,000 × 8 ÷ 300 ≈ 1,333 seconds, or about 22 minutes.
| File | Size | 100 Mbps | 300 Mbps | 1 Gbps |
|---|---|---|---|---|
| Song (MP3) | 5 MB | under 1 s | under 1 s | under 1 s |
| HD movie | 4 GB | about 5 min | about 2 min | about 30 s |
| 4K movie | 20 GB | about 27 min | about 9 min | about 3 min |
| Large video game | 100 GB | about 2 h 15 min | about 45 min | about 14 min |
These are best-case times. Real downloads also depend on how fast the server sends the file, on your WiFi, and on what else is using your connection.
Why your download looks slower than your plan
- You’re comparing bits to bytes. 40 MB/s on a 300 Mbps plan is actually excellent – it’s about 320 Mbps.
- The server is the bottleneck. Many download servers limit how fast they send each file.
- WiFi limits. Distance, walls and older devices often cap WiFi well below your plan. Our guide on how to boost your WiFi signal can help.
- Other devices are busy. Streams and updates on other devices share the same connection.
- Your storage is slow. On gigabit connections, an old hard drive can be slower than the internet itself.
To see your real network speed in Mbps – the same unit your provider uses – run our free speed test.
Other units you’ll see
| Unit | Meaning | Equals |
|---|---|---|
| Kbps | kilobits per second | 1,000 bits per second |
| Mbps | megabits per second | 1,000 Kbps |
| Gbps | gigabits per second | 1,000 Mbps |
| KB/s | kilobytes per second | 8 Kbps |
| MB/s | megabytes per second | 8 Mbps |
| GB/s | gigabytes per second | 8 Gbps |
You may also see MiB and GiB (mebibytes and gibibytes). They are based on 1,024 instead of 1,000 and are about 5–7% larger. Some operating systems show file sizes this way, which is why a “1 TB” drive appears as roughly 931 GB in Windows.
Frequently asked questions
Is 100 Mbps the same as 100 MB/s?
No. 100 Mbps equals 12.5 MB/s. To download at 100 MB/s, you would need a connection of about 800 Mbps.
Why do internet providers use Mbps?
Networking equipment has always been rated in bits per second, so it’s the industry standard. It also produces bigger, more impressive numbers.
Is 10 MB/s fast?
10 MB/s equals 80 Mbps – fast enough for several HD streams and most households, but slow for downloading large games every day.
How much speed do I actually need?
It depends on how many people and devices use the internet at the same time. Our internet speed calculator gives you a personalized recommendation in a few seconds.