A rate is a ratio between two types of measurements. Data transfer rate is the speed at which something can be transferred---for example, a video being downloaded from a website to your computer or a document being transferred from your computer's hard drive to an external hard drive. It's usually represented by showing how fast the device that's doing the sending can send a certain amount of data---for example, 50 Kilobytes per Second, which is abbreviated to 50KB/s.

- Skill level:
- Moderate

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## Instructions

- 1
Determine the size of the object being transferred. For this example, let's say you're downloading an online video. In your web browser's download box, beneath the name of the video, it should say the video size. Let's say this video is 100 megabytes (MBs).

- 2
Determine the data transfer rate. Again, this will be shown in your web browser's download box, beneath the name of the video. Suppose the video you are downloading is currently downloading at a speed of 50 kilobytes (KBs) per second.

- 3
Determine the relationship between the measurement unit shown in the data transfer rate (KB) and the measurement unit of the entire file (MB). If you don't know, simply perform a web search for "KB to MB ratio." In this case, there are 1000 KBs for every 1 MB.

- 4
Convert the measurement unit of the full file size (MB) to the unit shown in the data transfer rate (KB). To do this, set up an equation with two rates and then cross-multiply. If there is 1 MB for every 1000 KB, then there are "X" kilobytes for every 100 MBs (the video's file size). Refer to the picture for a clearer idea (in which the asterisks mean "times"). Eventually, you'll find that 100 MBs equals 100,000 KBs.

- 5
Set up another equation, this one comparing the newly-converted file size to the data transfer rate. If the video is downloading at 50 KBs per second, then you will download the entire 100,000 KBs of the video in "X" seconds. Again, refer to the picture to see each step of the math work. The final outcome---the value of "X"---is the amount of time the file will take to transfer. In this case, it will take 2,000 seconds.

- 6
Convert the final outcome into a more recognisable figure if need be. Since there are 60 seconds in a minute, simply divide 2,000 by 60. You'll get 33 1/3; so it will take 33 minutes and 20 seconds to download a 100 MB file that's downloading at a data transfer rate of 50 KB/s.