What Is A Megapixel?

A Megapixel is simply a unit of graphic resolution equivalent to one million. Or more precisely 1,048,576 (220) pixels. Megapixels are often used in marketing new camera sales because people always assume bigger is better. It's good for sales!

That said, if you have a photo and you want to figure out the Megapixel count of that image this is what you have to do. Simple multiply the resolution of the image then divide by 1 million.

For example this photo iPhone 6 Plus sample photo by Flickr user Janitors is 8 Megapixels at full resolution however when embedded below (on this webpage it's only 0.3 Megapixel)

iphone 6 sample photo - Icon Photography School
(620x465 ~0.3 Megapixel)

So if your photo has this resolution:
3264 x 2448

Do the following simple calculation:
3264 x 2448 = 7,990,272

7,990,272 / 1,000,000 = 7.990272

So this image would basically be 8 Megapixels or 8MP. As a general rule you just round up or down accordingly.

1024 x 768 = 786432
0.7 Megapixel

1600 x 1200 = 1920000
2 Megapixel

2048 x 1536 = 3145728
3 Megapixel

3264 x 2448 = 7990272
8 Megapixel

Here is a table of some common resolutions from 1 to 100 Megapixels.

If you want to determine how large you can print certain photos? Check this page.

More photography resources.