How to calculate transfer rate and needed bandwidth I have two questions:

1- If I want to transfer a photo via bluetooth, how should I find how long it takes to transfer? I mean the formula between the image size, bluetooth bandwidth and time.

2- If I want to transfer video in real time, how should I calculate the bandwidth is needed to transfer the video via bluetooth/WiFi? What's the formula between video resolution(VGA,2K,4K,etc) and transferring bandwidth if we want to do it in real-time?

For example: If I have 1920*1080*30(fps) video, I think I should multiply it by 3 or 4(respect to colored image type) then I have about 180~240 million bytes to transfer per second. So it means I need about 200MBps bit-rate! And I only should use 802.11n protocol for that! 

Did I calculate the things right?

EDIT: I found this calculator that I am not sure but I think it's the thing I was looking for (https://www.cctvcalculator.net/en/calculations/bandwidth-calculator/). what do you think about this? Why does it calculate local bandwidth bigger than network bandwidth? it's strange for me!
Your calculations are wrong. You have misunderstood the concept. The files may contain an amount of bits as you calculated but transferring that information is a bit different.

First of all, you send information as PACKETS. Here is an example packet type which is being used in Bluetooth.



The only place you send the actual information is called PAYLOAD. As you can see, payload is occupying a smaller area than you expected in a packet. The size of payload can smaller or larger depending which type of packet you are using, or which type of standards you are working with etc. And your bit rate is determined by which modulation type you use, how many bits your one symbol contains etc.

And not to forget, if your conditions are not perfect (which is the general situation) you WILL send some packets which is corrupt and you need to send them again. Which also reduces your actual bit-rate.

So there is different calculations for different combinations of the different techniques. 

I hope the answer is clear.

As always,
Have a nice day.