Iphone 6 = 12 MegaPixel photos
How many megapixels are useful in practice.
A megapixel rating tells you how many pixels there are in a photo.
If it measures 4,000 by 3,000 pixels, it’s a 12-megapixel photo.
If you halve the width of a 12MP photo, the megapixel rating drops to 3MP.
For most sharing destinations, 3MP is fine, while 8MP is enough for A4 prints and 4K TVs.
If you want to crop the photos, there’s no upper limit to the number of megapixels that might be useful.