Need to calculate the area of a shape, a room, or a plot of land? Enter your measurements into the area calculator above and get an instant result in square feet, square meters, hectares, or acres.
This tool handles common shapes (squares, rectangles, triangles, circles, and more) plus land area and acreage estimates. Pick your shape, plug in the numbers, and the calculator does the rest.
Area is the size of a surface measured in square units. Whether you need square footage for paint or wallpaper, acreage for a piece of land, or a quick geometry check, this page walks you through the formulas and shows you how to use the tool.
Area Calculator Tool to Measure and Calculate Area
The area calculator tool above supports multiple shapes. Select the shape that matches your project, enter the required dimensions, and the result appears instantly.
Here is how to use it:
- Choose a shape (rectangle, triangle, circle, etc.).
- Enter the measurements in your preferred units.
- Read the calculated area and convert to other units if needed.
The tool is a planning aid and estimation resource. For legal property boundaries or construction blueprints, work with a licensed surveyor or engineer.
How do I calculate my area? Start by identifying the shape. A room is usually a rectangle. A garden bed might be a circle or triangle. Once you know the shape, measure the sides (or radius), and either use the formula below or let the calculator handle it.
Area Formulas for Every Shape
Every shape has its own equation. Below are the area formulas for the most common shapes, along with tips for using each one.
Square Area Formula and Area of a Square
A square has four equal sides. The square area formula is:
Area = side × side (or s²)
If one side is 10 feet, the area of a square is 100 square feet. That's it. One measurement is all you need.
Rectangle Area Formula and Area of a Rectangle
The rectangle area formula is the product of the length and width:
Area = length × width
This is the go-to formula for rooms, walls, and rectangular plots. A room that is 12 feet by 15 feet has an area of 180 square feet.
What is the perimeter of a rectangle? Perimeter = 2 × (length + width). Perimeter measures the distance around the edges, not the surface inside. More on the relationship between perimeter and area below.
How to calculate the area of an uneven rectangle? If opposite sides are not equal, you probably have a parallelogram or trapezoid. Measure carefully and use the matching formula from the sections below.
Triangle Area Formula and Area of a Triangle
The triangle area formula uses base and height:
Area = ½ × base × height
The height must be perpendicular to the base. For a right triangle, the two legs serve as the base and height, making the calculation straightforward.
How to get the area of a triangle with 2 sides? If you know two sides and the included angle, use:
Area = ½ × a × b × sin(C)
If you know all three sides, use Heron's formula:
- Calculate the semi-perimeter: s = (a + b + c) / 2
- Area = √[s × (s − a) × (s − b) × (s − c)]
Circle Area Formula and Area of a Circle
The circle area formula uses the radius (the distance from the center to the edge):
Area = π × r²
A circle with a radius of 7 meters has an area of about 153.94 m². If you only know the diameter, divide it by 2 to get the radius.
What is the area and perimeter of a circle? The perimeter of a circle is called the circumference: C = 2 × π × r. The area measures the surface inside; the circumference measures the distance around.
Area of a Parallelogram
A parallelogram is like a tilted rectangle. Its formula uses the base and perpendicular height:
Area = base × height
Do not use the slanted side length as the height. The height is the straight vertical distance between the two parallel sides.
Trapezoid Area Formula
A trapezoid has one pair of parallel sides. The trapezoid area formula averages those two sides and multiplies by the height:
Area = ½ × (base₁ + base₂) × height
This works for any trapezoid, whether symmetric or not.
Ellipse Area Formula
An ellipse looks like a stretched circle. It has two radii: a semi-major axis (a) and a semi-minor axis (b).
Area = π × a × b
When a and b are equal, the ellipse becomes a circle and the formula simplifies to π × r².
Quadrilateral and Polygon Area Formulas
For a general quadrilateral with four unequal sides, there is no single simple formula. The most reliable approach:
- Split the quadrilateral into two triangles using a diagonal.
- Calculate the area of each triangle separately.
- Add them together for the total area.
How to calculate the area of land with 4 unequal sides? Use the method above. Measure one diagonal and the perpendicular heights from that diagonal to each opposite vertex.
For regular polygons (pentagons, hexagons, octagons), use:
Area = ½ × perimeter × apothem
The apothem is the distance from the center to the middle of any side. So, where does the hexagon area formula come from? A regular hexagon splits into six equilateral triangles, and summing their areas gives (3√3 / 2) × s², which is equivalent to the perimeter-apothem formula.
What quadrilateral has the largest area? Given four fixed side lengths, the quadrilateral with the largest area is a cyclic quadrilateral (one whose corners all lie on a circle). Given a fixed perimeter, the square encloses the most area of any quadrilateral. In fact, among all shapes with a given perimeter, the circle has the largest area.
Calculate Land Area and Acreage for a Plot of Land
Calculating land area follows the same geometry principles, just at a larger scale. For a rectangular plot of land, multiply length by width. For irregular shapes, divide the tract of land into simpler shapes, calculate each, and sum the results.
Common land area units:
- 1 acre = 43,560 square feet
- 1 hectare = 10,000 square meters (about 2.471 acres)
- 1 square mile = 640 acres
To calculate acreage, find the total area in square feet and divide by 43,560.
How to calculate land area with different sides? Break the piece of land into triangles or rectangles. Measure each section, calculate the area of each, and add them up. For highly irregular shapes, a GPS survey or map-based tool gives more reliable results.
These calculations are estimates. Legal property descriptions, zoning decisions, and real estate transactions require a licensed surveyor.
Google Maps Area Calculator: Measure the Area on a Map
A Google Maps area calculator lets you measure land area by clicking points on a satellite view. You trace the boundary of a piece of land, and the tool calculates the enclosed area automatically.
How to calculate land area from Google Maps:
- Open a map-based area tool.
- Zoom into the property or tract of land.
- Click each corner or boundary point to create a polygon.
- The tool calculates the total area in your chosen unit (square feet, acres, hectares, etc.).
Some tools also let you import a KML file with predefined coordinates, which is helpful for larger or complex parcels.
Keep in mind that satellite imagery can have slight offsets. Map-based measurements are useful for planning and estimation, not for legal surveys.
Map Area Calculator vs. Google Maps Area Calculator
The terms "map area calculator" and "Google Maps area calculator" are often used interchangeably. The difference is mainly about the underlying map provider.
- A Google Maps area calculator specifically uses Google's satellite imagery and mapping data.
- A map area calculator may use Google Maps, OpenStreetMap, Bing Maps, or other providers.
Both work the same way: you click points, the tool calculates the polygon area. The accuracy depends on how precisely you place the points and the quality of the imagery. For most estimation purposes, either approach works fine.
Roof Area: Estimate and Calculate
Estimating roof area starts with the footprint of the building. The footprint is the area the structure covers on the ground (usually a rectangle or combination of rectangles).
A flat roof has the same area as the footprint. For a pitched roof, you need to account for the slope:
Roof area = footprint area × roof pitch multiplier
Common roof pitch multipliers:
- 4/12 pitch: multiply by 1.054
- 6/12 pitch: multiply by 1.118
- 8/12 pitch: multiply by 1.202
- 12/12 pitch: multiply by 1.414
A building with a 1,500 square foot footprint and a 6/12 pitch has an estimated roof area of about 1,677 square feet.
This estimate helps you plan the amount of roofing materials needed. Complex roof shapes with dormers, valleys, or multiple sections should be measured section by section for better accuracy.
Perimeter and Area: How They Relate
Perimeter measures the distance around a shape. Area measures the surface inside. They use different units: perimeter is in linear units (feet, meters), while area is in square units (square feet, m²).
Two shapes can have the same perimeter but very different areas. A long, narrow rectangle and a square can share the same perimeter, but the square will always have more area. Among all shapes with a given perimeter, the circle encloses the most area.
When do you need both? Fencing a yard requires the perimeter. Seeding or covering that yard requires the area. Many projects need both calculations.
Area Converter: Square Feet, Hectares, and Acreage
The area calculator includes a built-in area converter. Here are the most common conversions:
- 1 square foot = 0.0929 square meters
- 1 square meter = 10.764 square feet
- 1 acre = 43,560 square feet = 4,046.86 square meters
- 1 hectare = 2.471 acres = 107,639 square feet
- 1 square mile = 640 acres = 259 hectares
To convert square footage to acreage, divide by 43,560. To convert square meters to hectares, divide by 10,000.
How to calculate area in mm? Use the same formulas. Just enter millimeters as your unit. The result will be in square millimeters (mm²). To convert to m², divide by 1,000,000.
The calculator lets you switch between measurement units so you do not need to convert manually.
How to Find the Area and Estimate With This Area Calculator Tool
Here is a quick summary of how to find the area of any shape using this online tool:
- Identify the shape. Is it a rectangle, triangle, circle, or something else?
- Measure the dimensions. Use a tape measure for rooms, a map tool for land, or known values for homework.
- Select the shape in the calculator above.
- Enter your measurements in the unit that matches (feet, meters, inches, etc.).
- Read the result. Convert to other units if needed using the area converter.
For irregular shapes, break them into simple shapes, calculate each area separately, and add the results. This works for oddly shaped rooms, gardens, and plots of land.
How to calculate the area of an irregular shaped piece of land? Divide it into triangles and rectangles. Calculate each section, then sum the total area. For very complex boundaries, a map area calculator with polygon tracing is faster and often more accurate.
This area calculator gives estimates for planning and learning. It covers common shapes, land area, acreage, and unit conversions all in one place. For professional surveying, engineering, or legal purposes, consult a qualified professional.