How to Estimate Square Footage
It’s a risky game
Too much of a good thing and you have a bunch of extra stone and nowhere to put it. Too little, and you have to drive back and pick up more. To save yourself time and money, look at the shape of your project and take a few simple measurements. Use this information to calculate the square footage. Since this isn’t math class, you just need to get a general idea of the area of your project. Take that with you to the stone yard and you are on your way to the coolest yard on the block.
Note: Always measure in feet! As interesting as it is to know the square inchage, or the square meterage, area coverage for stone is almost always described in FOOTage.
The Rectangular = length x width
There is nothing uncool about being a square, or rectangle for that matter. You have the quickest calculation! Even if your space isn’t perfectly rectangular, this formula will work for you.

Measure length and width in feet.

Multiply the two.

Give yourself a pat on the back.
How easy was that? Use this method for pathways. Straight or twisted, you just need the path length and width.
Symbol of power and strength, the triangle is a dynamic shape for any project. To get the square footage of your powerhouse project, measure the base of the triangle (any side will work) and measure from the center of the base to the most distant point. Take half of the base length and multiply by the height.
The Pie = 3.14 x radius 2
Some of the best things in life are round. Pies. Pizzas. Hamburgers. Cookies. Certain cakes. Analogue clocks pointing to lunch time. And your project. Circular, round, or roundish, all you need to measure is the distance from the center to the edge (i.e. the radius). Square that distance (distance x distance) and multiply by 3.14.
Only have half a circle? Use the same formula and divide by 2. Mmm…Nothing like a slice of a tasty, tasty project!
The Free Spirit = a little more complicated.
My, aren’t we creative and complex. Simple geometry can’t contain your project. Of course that makes things a little more interesting when we are finding square footage. The trick is to divide up your free form space into smaller, more geometric pieces. Use the formulas from above and add the square footage for each section together.