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Irregular polygon area calculator

The area of any polygon — regular or not, convex or concave — from its corner coordinates. Enter the vertices in order and the shoelace formula returns the exact area, plus the perimeter, the centroid and whether the points run clockwise or counter-clockwise, with a drawing of the shape. Ideal for land plots and CAD sketches.

Related tools

All Geometry tools →
Regular polygon area calculatorCompute the area of a regular polygon from its number of sides and side length.Polygon diagonals calculatorHow many diagonals a polygon has, from its number of sides: n·(n−3)/2 — because each vertex connects to all others except itself and its two neighbours. It also names the polygon and gives the number of triangles it splits into and the sum of its interior angles.Regular polygon calculatorEvery measure of a regular polygon from the number of sides and the side length: the area, perimeter, interior and exterior angles, the sum of interior angles, the apothem (inradius), the circumradius and the number of diagonals. One entry, the full geometry — for triangles through many-sided polygons.Regular polygon perimeter calculatorCompute the perimeter of a regular polygon from its number of sides and side length.Annulus (ring) area calculatorCompute the area of a ring from its outer and inner radius.Area calculatorCompute the area of a rectangle, square, circle or triangle.Circle sector area calculatorCompute the area and arc length of a circle sector from its radius and angle.Cone surface area calculatorCompute the total surface area and slant height of a cone from its radius and height.

Open Irregular polygon area calculator and you get an answer straight away, with no account to create. You will find it under Geometry, with Regular polygon area calculator and Polygon diagonals calculator for the neighbouring cases.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What does Irregular polygon area calculator do?

The area of any polygon — regular or not, convex or concave — from its corner coordinates. Enter the vertices in order and the shoelace formula returns the exact area, plus the perimeter, the centroid and whether the points run clockwise or counter-clockwise, with a drawing of the shape. Ideal for land plots and CAD sketches.

What does a concrete case look like?

(0,0), (4,0), (4,3), (0,3) → A = 12 — the tool shows every step in between, not just the final figure.

When would I actually use this?

Homework and site work alike: how much paint a wall takes, how much water a tank holds, whether a corner is square — and, on the coordinate side, the slope between two points, the distance across a plan, the midpoint of a span.

What is the most common mistake?

Mixing units inside one shape. Entering a length in centimetres and a width in metres gives an area wrong by a factor of a hundred, and the result looks perfectly plausible.

How is Irregular polygon area calculator different from Regular polygon area calculator?

They sit next to each other but answer different questions: Regular polygon area calculator is the one to open when you need it to compute the area of a regular polygon from its number of sides and side length. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

Polygon diagonals calculator is the closest one after this: How many diagonals a polygon has, from its number of sides: n·(n−3)/2 — because each vertex connects to all others except itself and its two neighbours. It also names the polygon and gives the number of triangles it splits into and the sum of its interior angles.

What else is worth having open alongside it?

Regular polygon calculator and Regular polygon perimeter calculator — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

The formulas are the classical ones and the results are exact to the precision shown — geometry does not change with the year or the country, so nothing here needs updating.

Further reading

All guides →
How-toCircle: Circumference and AreaCircumference is 2πr, area is πr². Here's how radius, diameter and π fit together, both formulas worked through, and how not to mix them up.ExplainerThe Pythagorean Theorem ExplainedIn a right triangle, a² + b² = c². Here's what the formula means, a worked example, how to find any side, and where it's used in real life.How-toHow to Calculate VolumeVolume is the space inside a shape. Here's how to find it for boxes, cylinders and spheres, and why keeping your units consistent is the whole game.How-toHow to Calculate the Square Metres of a RoomFind a room's area by multiplying length by width. Here's the method for rectangular, L-shaped and round rooms, and why area drives your material orders.How-toHow to Find the Area of a Triangle: Base × Height and Heron's FormulaTwo reliable ways to find a triangle's area: half base times height when you know the height, and Heron's formula when you only know the three sides.How-toHow Many Tiles Do You Need? (Floor and Wall)Estimate tiles from the area to cover and one tile's size, then add for cuts and waste. Here's the method, with an example and the 10% rule.