Polygon Area & Irregular Square Footage
Calculate the exact surface area of complex and irregular multi-zone polygons. Decompose composite site boundaries into standard rectangles, triangles, and circular sectors with live layer-depth cubic yard conversions.
Active Layout Zones
Rectangle
Zone Area: 300.0 sq ft
Right Triangle
Zone Area: 75.0 sq ft
Total Composite Area
How to Calculate the Area of an Irregular Polygon
Most job sites are not clean rectangles. The reliable way to measure an irregular polygon is to break the outline into shapes you already know. Split it into rectangles, right triangles, and circle segments, work out the square footage of each piece, then add the pieces together. That sum is the area of the irregular polygon.
This irregular polygon area calculator does the adding for you. Enter each rectangle, triangle, or circle as its own zone and it keeps a running total of square footage, then converts that area into cubic yards at the depth you plan to pour or spread.
Regular Polygons vs Irregular Polygons
Regular Polygons
Regular polygons have equal sides and equal angles, like a stop sign octagon or a garden gazebo. For those the apothem formula works: Area = ½ × Perimeter × Apothem. You only need the side length and the number of sides.
Irregular Polygons
Irregular polygons have sides and angles that vary, which covers most yards, patios, and driveways. Surveyors solve these with the shoelace formula from corner coordinates, the standard irregular polygon formula for mapped points. On site you rarely need it. Measure each rectangle and triangle with a tape, total the areas, and you have the area of the irregular polygon without any coordinate math.
Authentic Field Surveying FAQ
Split the "L" into two separate rectangles by extending an imaginary line through the inner corner. Measure Length × Width for both individual segments, then add them as two Rectangle zones in the engine above.
For quarter-circle corners, measure the radius (distance from the corner to the curve edge). Add a Circle zone in the engine, but remember the output is a full circle—you will need to manually divide by 4 for a quarter-arc.
An oval (ellipse) can be approximated by measuring the longest axis (Length) and the widest axis (Width). Multiply (Length/2) × (Width/2) × 3.14159.
You likely forgot the depth factor or compaction allowance. Even if your 2D area is 100% accurate, subgrades absorb material, formwork bows, and crushed stone compacts by 15%. Always apply a 10% safety overage.
Consumer smartphone GPS has a variance radius of 15 to 30 feet, which is entirely insufficient for material ordering. You must use a physical measuring wheel or 100ft tape measure for hardscape volumes.