Script to find the area of map shapes in Adobe Illustrator, scaled to a hex grid for worldbuilding.

GetMapShapeArea.jsx

/*
Save this file with a jsx extension and access from the File > Scripts menu

Currently, this assumes your map utilizes a 24 mile hex. This is necessary to have a scale
factor by which to to multiply the area of your map shape to get the area in mi/km.

If your map uses a different scale, select a single hex and run this script. Replace the inches
value with the value in hexAreaInchesMap, select your shape, and run again to get sq mi / km.

By default, this rounds up the mi/km. Km is +/- 1 due to rounding. Will fix later.

* original AI script: https://gist.github.com/bryanbuchanan/11387501
* format JS number with commas: https://stackoverflow.com/a/2901298
*/

var decimalPlaces = 10;				// rounding to 10 places because math
var hexAreaMileActual = 498.8307291667;		// sq mi area of a 24 mile hex
var hexAreaInchesMap = 0.0523425444;		// sq in area of your map's hex

if (app.documents.length > 0) {

	if (app.activeDocument.selection.length < 1) {
		alert('Select a path');
	} else if (app.activeDocument.selection[0].area) {
		// Individual Items
		var objects =  app.activeDocument.selection;
	} else if (app.activeDocument.selection[0].pathItems) {
		// Group/Compound Shape
		var objects = app.activeDocument.selection[0].pathItems;
	} else {
		alert('Please select a path or group.');
	}

	// Collect info
	var totalArea = 0;
	for (var i=0; i<objects.length; i++) {
		if (objects[i].area) {
			var totalArea = totalArea + objects[i].area;
		}
	}

	// Conversions
	var ppi = 72;
	var areaIn = totalArea / ppi / ppi;
	if (areaIn < 0) var areaIn = -areaIn;

	// Scaled map area calculations
	var scaleFactor = hexAreaMileActual / hexAreaInchesMap
	var geographicAreaMi = scaleFactor * areaIn.toFixed(decimalPlaces)
	var geographicAreaKm = geographicAreaMi * 2.58999
	var geographicAreaFmtMi = Math.ceil(geographicAreaMi).toString().replace(/\B(?=(\d{3})+(?!\d))/g, ',')
	var geographicAreaFmtKm = Math.ceil(geographicAreaKm).toString().replace(/\B(?=(\d{3})+(?!\d))/g, ',')

	// Display
	alert('\
	' + i + ' shape(s) selected \n\
	File Area: \
	' + areaIn.toFixed(decimalPlaces) + ' sq in \n\
	Map Area: \
	' + geographicAreaFmtMi + ' sq mi \
	' + geographicAreaFmtKm + ' sq km'
	);
}

For a full description of the purpose of this fork, see: https://embers.nicejacket.cc/blog/2019/05/28/measuring-area-in-illustrator-to-scale/

The purpose here is to be able to calculate the in-world area of a border or other shape representing a political, linguistic, etc., region, scaled to a hex grid of a fixed size. In the above code, the common 24-mile hex is used. To use another size hex, run this code on a selected hexagon of your map's size, and replace the inches squared value of hexAreaInchesMap, and calculate the actual area of that size hex with:

A = (3 × √3 × s²) / 2

...where A is the area of the hex, and s is the length of one side of the hex.