Baby size

So I have been keeping thorough track of baby's measurements weekly. I take out my ruler and try to picture how big my baby is. 1.2-1.5 inches this week! Seems so big already! 
Well, try this for an experiment. On average, baby is usually over 18 inches. If you take a ruler and put it vertically on your stomach (top to bottom) the ruler only measures 12 inches and I was totally shocked to see that it pretty much goes across my entire abdomen and chest. And just think, that's not even the whole length of the baby. Just try and experiment this for yourself. It's fun :)