There is a lot of confusion around internet speeds advertised by Internet Service Providers (ISPs) and the actual download speeds you get. If you’ve ever taken an internet speed test, you’ve probably noticed that the numbers shown in your results are closer to the advertised speed, even though it appears that the actual download speed is much lower. There’s nothing wrong here, it just has to do with how internet speed is measured.
Your internet speed is measured in bits, while bytes are the more commonly used storage metric. Basically, a bit is the smallest unit of digital information and has a value of 0 or 1. A byte, on the other hand, is relatively larger, comprising eight bits. Since this is what systems care about from a storage perspective, we measure file size in bytes. But for data transfer speeds, bit has long been the standard since it represents the smallest form of data – and that’s how data is transmitted across the Internet, one bit at a time.
These days, internet speed or file size are almost never measured in single bits or bytes, respectively. Indeed, these are extremely small numbers by modern standards and we are dealing with much larger files. Instead, megabits or megabytes are now more commonly used, which is essentially 1 million bits or bytes, respectively.
Bits make more sense for network speeds
When we talk about data transfer over a network or the Internet, precision matters, and that is why bits or megabits emerge as the most suitable choice. Data transfer over the Internet does not always occur in an orderly manner, as is the case with local file transfer on a PC. Apart from this, the data can come from different sources. So, for precise measurements, bits are the best choice since they are the smallest unit of data, and this is what ISPs traditionally advertise.
And this is where the confusion begins. In short, megabits per second (Mbps or Mb/s) and megabytes per second (MBps or MB/s) look very similar. But the thing to remember is that the lowercase “b” represents bits, while the uppercase “B” represents bytes. Additionally, when you run a speed test, it displays internet speed in megabits per second, whereas browsers like Google Chrome usually display it in megabytes per second. To the average user, both represent the same thing, your Internet speed.
As for storage drives, whether it’s a hard drive or an SSD, they store data as bytes, a collection of eight bits, instead of the smallest unit. That’s why when we talk about disk capacity or file size, it is usually expressed in kilobytes (KB), megabytes (MB), gigabytes (GB), terabytes (TB), petabytes (PB), etc. Therefore, the transfer speeds you see on PCs are also in megabytes per second (MB/s).
Converting megabits to megabytes
If you want to convert Mbps to Mbps, simply divide the first one by eight. Similarly, to convert MB/s to Mb/s, multiply the first by eight.
For example, if your internet speed is 200 Mbps, the calculation works out to 25 Mbps (200 Mbps / 8). Ignoring overhead and other real-world limitations, this means that it would take about a second to download a 25MB file. Of course, the actual download speed is comparatively lower, as many factors come into play, including optimal router placement, wireless interference from other devices, as well as the speed of the download source itself.
So the next time your ISP tells you internet speed in Mbps, but your browser shows it in Mbps, remember that they use different units for the same thing. The former is the standard adopted for measuring data transfer rates, while systems understand the latter better, given how file sizes are measured.
