Confusing megapixels with file size

A 48 megapixel camera produces 48 megabyte images.

The megapixel counts pixels, not bytes: 48 MP is 48,000,000 pixels. Uncompressed such an image occupies about 144 MB, because each pixel needs three bytes for red, green and blue. A JPEG of the same shot typically lands between 8 and 20 MB depending on subject and quality setting.

Megapixel and megabyte sound alike, and both figures appear in the same product datasheets. File size additionally depends on compression, which is determined by the image content — so it is not a fixed property of the camera.

Treat pixel count and file size separately. To estimate the uncompressed size, multiply the pixel count by three bytes. For storage planning check the actual file size on your own device, because compression depends on the subject.