Land Surveying & Planimetry Suite

Area of Irregular Polygon Calculator & Square Foot Calculator

A visual square foot calculator, sq ft calculator, and sqft calculator: draw a shape and calculate area, compute land dimensions calculator metrics, and solve odd shape square footage calculator plans.

Interactive Polygon Canvas Click on canvas to add vertex corners

Calculated Square Footage

Total Area (sqft calculator)
4,500 sq ft
0.103 Acres / 418.06 m²
Perimeter (Boundary)
320.0 ft
Linear boundary distance
Corners (Vertices)
6
Connected points
Coordinates List (x, y)

Dimensions (Width x Length Calculator) rectangle calculator

Room Square Footage figure out area

Net Floor Area (sq ft calculator)
1,000 sq ft
25 ft × 40 ft
Material with 10% Waste
1,100 sq ft
Tile, hardwood, or carpet
Perimeter (Baseboards)
130.0 ft
2 × (W + L)

Multi-Room Floor Plan (Area of a House Calculator)

Room Name Length (ft) Width (ft) Room Sq Ft Action
Total House Square Footage
1,850 sq ft
Sum of all living spaces

Mathematical Surveying: How to Figure Out Area of an Irregular Polygon

Standard geometry formulas easily handle rectangles ($W \times L$) and triangles. However, real-world land boundaries, property deeds, architectural floor plans, and landscaping beds often consist of non-standard geometries. Our area of irregular polygon calculator and odd shape square footage calculator leverages the Gauss Shoelace Formula (also known as the Surveyor's formula) to calculate exact area from ordered boundary vertices.

The Shoelace Formula (Surveyor's Algorithm)

Given a set of $n$ vertices arranged counterclockwise in a 2D Cartesian plane $(x_1, y_1), (x_2, y_2), \dots, (x_n, y_n)$:

Gauss Shoelace Equation:
Area = 0.5 × | (x₁y₂ + x₂y₃ + ... + xₙy₁) − (y₁x₂ + y₂x₃ + ... + yₙx₁) |
The algorithm sums the cross-products of coordinates in diagonal pairs (like tying shoelaces), taking half the absolute value of their difference.

Converting Square Feet to Acres (Land Dimensions Calculator)

When utilizing our land dimensions calculator for rural parcels, subdivision lots, or commercial property, square footage easily converts to imperial acres:

1 Acre = 43,560 Square Feet (sq ft)
Acres = Total Sq Ft / 43,560
Example: A property measuring 130,680 square feet equals exactly 3.0 acres.

Frequently Asked Questions

How to use the "draw a shape and calculate area" feature? +
Click anywhere on the interactive canvas grid to drop boundary vertices. As you place each corner, the polygon connects dynamically, computing total square footage, perimeter linear footage, and acreage in real time based on your selected grid scale.
How do you calculate the square footage of an L-shaped room? +
An L-shaped room can be calculated by splitting the room into two independent rectangles, calculating the area of each (Width × Length), and adding the two square footage values together. Alternatively, click our "L-Shape Preset" on the canvas above!