Your internet plan says 200 Mbps. Your download client shows 20 MB/s. Something feels off. You are being cheated, right? Actually, no. Those two numbers are describing exactly the same speed — you just need a single conversion to understand why.
The One Rule You Need
Bits and bytes are both units of digital information, but they are different sizes. There are 8 bits in 1 byte. That is the entire explanation. The lowercase "b" in Mbps stands for bits. The uppercase "B" in MB/s stands for bytes. ISPs advertise in megabits per second because the number sounds larger. Your download manager shows megabytes per second because that is what files are measured in.
So a 200 Mbps connection will download files at roughly 25 megabytes per second — assuming no overhead, which we cover below. If your download client is showing 22–24 MB/s on a 200 Mbps plan, your connection is performing correctly.
What About Overhead?
Real-world download speeds are always slightly below the theoretical maximum because your connection carries more than just your file data. Every data packet includes headers — addressing information telling routers where the data came from and where it needs to go. This is called protocol overhead, and it typically accounts for 5–10% of your bandwidth.
Our speed test applies a standard 1.06 overhead compensation factor to report the speeds your application actually sees, rather than raw line throughput. This is why a speed test result is more useful than raw modem statistics.
Mbps vs Mbps: The Other Confusion
There is a second, less common confusion: Mbps (megabits) vs MBps (megabytes) vs Mibps (mebibits). Some tools report in mebibits, where 1 mebibit = 1,048,576 bits, instead of the standard 1,000,000 bits per megabit. The difference is about 4.8%. Our speed test uses megabits (SI standard) by default, matching how your ISP measures and advertises your plan, so the numbers are directly comparable.
Quick Reference
- 25 Mbps plan → ~3.1 MB/s download speed
- 100 Mbps plan → ~12.5 MB/s download speed
- 200 Mbps plan → ~25 MB/s download speed
- 500 Mbps plan → ~62.5 MB/s download speed
- 1 Gbps plan → ~125 MB/s download speed
If your real-world downloads are significantly below these numbers on a consistent basis — say, getting 8 MB/s on a 100 Mbps plan — run a speed test to confirm whether the problem is your ISP delivering less than you pay for, or something on your local network throttling the connection.