Mbps vs MB/s: why your download looks eight times slower
Mbps (megabits per second) is what internet providers and speed tests report; MB/s (megabytes per second) is what download managers, game launchers and browsers usually show. Because a byte is 8 bits, divide Mbps by 8 to get MB/s: a 100 Mbps plan downloads at no more than 12.5 MB/s.
Why the same connection shows two numbers
Nothing is wrong when your 300 Mbps plan shows a download at 35 MB/s. The two figures measure the same flow of data in different units:
- Providers and speed tests count bits. A connection sends a stream of bits down a cable or through the air, so networking has always measured speed in bits per second. Plans, broadband labels and speed test results all use Mbps or Gbps.
- Apps count bytes. Files are stored and sized in bytes, so software that writes a file to disk reports how many bytes per second arrive: kB/s, MB/s or GB/s.
The capital letter is the whole difference. b is a bit, B is a byte, and 1 B = 8 b. So 1 MB/s = 8 Mbps, and 300 Mbps ÷ 8 = 37.5 MB/s, the most that plan can show in a download app before any overhead.
What your plan looks like in a download app
| Plan speed | Best case in MB/s | At 90% efficiency |
|---|---|---|
| 50 Mbps | 6.25 MB/s | 5.6 MB/s |
| 100 Mbps | 12.5 MB/s | 11.25 MB/s |
| 300 Mbps | 37.5 MB/s | 33.75 MB/s |
| 500 Mbps | 62.5 MB/s | 56.25 MB/s |
| 1 Gbps (1,000 Mbps) | 125 MB/s | 112.5 MB/s |
The "best case" column is a straight division by 8. Real downloads lose some capacity to protocol overhead and share the line with other devices, so the 90% column, the same figure the download time calculator offers as its optional efficiency setting, is closer to what a good connection shows. For other values, use the Mbps to MB/s converter.
Reading the numbers on common screens
- Game launchers and browsers usually show MB/s. Multiply by 8 to compare with your plan: a launcher at 55 MB/s is moving 440 Mbps.
- Speed test sites show Mbps, the same unit as your plan, so the result can be compared directly. The speed test checker does that comparison for you.
- Router and system monitors vary. Many show kbps or Mbps for network traffic, while file-copy windows on the same computer show MB/s. Check the letter case before comparing.
- Some tools use binary units such as MiB/s (mebibytes per second), sometimes still labelled "MB/s". 1 MiB/s = 8.388608 Mbps, about 5% more than 1 MB/s, so a reading from such a tool converts to slightly more Mbps.
Labels such as "Mb/s" and "Mbit/s" mean the same as Mbps. "MBps" means megabytes per second, but it is easy to misread, which is why this site writes MB/s.
Is my download slow? A quick check
Take the MB/s figure from your download, multiply by 8, and divide by your plan speed:
share of plan = (MB/s × 8) ÷ plan Mbps 55 MB/s on a 500 Mbps plan = 440 ÷ 500 = 88%
88% on a wired computer is a healthy result. If the same sum gives 30% or 40%, the bottleneck may be Wi-Fi, a busy line or the server you are downloading from. A single download is only as fast as the server sending it, so one slow download proves little; a speed test to a nearby server is the better check.
The reverse sum is useful too. To know what reading a plan should give, divide by 8: on a 1 Gbps plan, a wired test typically tops out around 940 Mbps because of Ethernet overhead, which is 117.5 MB/s in a download app. For MB/s readings of any size, the MB/s to Mbps converter does the multiplication.
Why providers don’t just use MB/s
Bits per second is the standard unit for data transmission across networking equipment, standards and regulation, and it has been since long before home broadband. Regulators set benchmarks in it (the FCC's 2024 broadband benchmark is 100 Mbps down and 20 Mbps up), and every plan in a market uses it, so plans stay comparable. The bigger number is a side effect, not a trick, but it does mean you need the factor of 8 whenever you compare a plan with a file.
If the idea of bits and bytes is itself the confusing part, bits vs bytes explains where the 8 comes from and why storage uses bytes.
Key takeaways
- Mbps is megabits per second (plans, speed tests); MB/s is megabytes per second (download apps).
- Divide Mbps by 8 for MB/s; multiply MB/s by 8 for Mbps. 100 Mbps = 12.5 MB/s.
- Lowercase b is a bit, uppercase B is a byte. MiB/s is a binary unit: 1 MiB/s = 8.388608 Mbps.
- To judge a download, convert it to Mbps and compare with your plan; about 85% or more on a wired connection is healthy.
Frequently asked questions
Is 1 MB/s the same as 1 Mbps?
No. 1 MB/s (megabyte per second) is eight times faster than 1 Mbps (megabit per second): 1 MB/s = 8 Mbps.
How many MB/s is 100 Mbps?
12.5 MB/s at most. With about 10% lost to overhead, expect around 11 MB/s in a download app on a good connection.
Why does my 1 Gbps plan download at about 110 MB/s?
1 Gbps is 125 MB/s at most. Ethernet overhead limits a wired test to about 940 Mbps, which is 117.5 MB/s, and other traffic or the server can take a little more off.