How many megabytes does a chest x ray require?

depends on imaging system. they range from 5 to 10 megapixels each. each megapixel requires 1.5 megabytes of storage because of 12 bit grayscale.

So... best equipment produces 10 megapixel image requiring 15 megabytes of information to be stored. The images are stored in jpeg2000 format which cuts the size in half using nonlossy compression.

So summary it takes up to 7.5 megabytes of space on the hospital hard drive to store one xray.