It's a percentage. Where the difference between 16 and 24 is a 50% improvement (24-16)/16 or 8/16=50%. So the pixel density difference between 16Mpx and 24Mpx is 50%. That's huge. The difference between 24Mpx and 10 Mpx is 140%- an even larger difference. There is more in play here when you compare camera to camera. Generations of the same sensor are vastly different, and sensors from one manufacturer to another are not even on the same planet. (I exaggerate to make the point.) Looking back recently at images I made with my Coolpix E995 in 2002, I was pleasantly surprised at the quality of those 2.+Mpx images. I'm way off the subject here, but my point is that Megapixels, while important, aren't the only thing. Of course, when I bought a new camera, I didn't buy a D90, which is a perfectly acceptable camera, but obsolete. I bought a D600. I got a more advanced camera, and along with that better camera, I got a 24Mpx sensor. The biggest difference between the E995 and the D600 is CONTROL. The E995 could be controlled, but it was slow and a hassle. Manual control of the D600 is quick and easy. The point at which we can say we have enough Mpx is here. If you think 36Mpx benfits you, buy a D800. If not, there is a whole range of great cameras which are cheaper, and produce great pictures. Nikon nor anyone else has figured out how to to automate a camera to go into AnselAdams mode or to turn on the ElliotPorter effects. That day is a long way off. I don't think I'll ever see that.