How to calculate the area of an irregular shape in Adobe Illustrator?

There’s unfortunately no way of getting the area in Illustrator (CS6/CC) natively that I know of.

You may have more luck with scripts.

I found one here that seems to work.

The code seems rather simple:

alert("Area & Length (inches)\nArea: " + (Math.abs(app.activeDocument.selection[0].area/5184).toFixed(3)) + "\nLength: " + (app.activeDocument.selection[0].length/72).toFixed(3));

You could also convert these measurements from inches to centimeters. The source page seems to go into some descriptions on how to customize it.

Getting area in CS-CS5

That being said you can look at it through an unsupported feature in CS5 and below (down to CS I believe) by clicking:

CTRL+ALT+SHIFT+F12

or

CMD+OPTION+SHIFT+F12

Select your path then open the object section and look at the area read-out:

I can’t tell you how to interpret that area read-out (I’d assume points) but you can use it as a point of comparison. No pun intended.

Do be careful with this feature as it is unsupported and could cause grief.

Source and alternative methods