A digital imaging question...

[Route 66]

First of all, I hope I'm using the correct terminology here...

I know that by multiplying the pixel height x the pixel width will give you the total megapixel count of the image. Example: 1600 x 1200 = 1920000 or 2 megapixels.

Is this also the the megabyte count?

In other words, how do you convert megapixels into megabytes to determine the size of the image?

Thanks