Area Calculator
Calculate the area of 10 shapes including square, rectangle, triangle, circle, and polygon. Metric and imperial units with square-unit conversions.
Select a shape and enter dimensions.
Area Calculator: Find the Area of Any Common Shape
Area is the amount of two-dimensional space a shape covers, measured in square units such as square meters or square feet. This calculator computes the area of ten common shapes and converts the result between units, which makes it useful for painting walls, laying carpet or tile, measuring land, and any project where you need to know how much surface you are working with. Select a shape, enter the dimensions, and the exact area appears instantly.
Rectangle: length × width
Triangle: (1/2) × base × height
Circle: π × r²
Parallelogram: base × height
Trapezoid: (1/2) × (a + b) × height
Ellipse: π × a × b
Rhombus: (d₁ × d₂) / 2
Circle sector: (angle/360) × π × r²
Regular polygon: (1/4) × n × a² × cot(π/n)
What Area Means and Where It Is Used
Every flat shape has an area, and knowing it answers everyday questions: how much paint covers a wall, how many tiles fit a floor, or how large a plot of land is. Builders, decorators, gardeners, and students all rely on area formulas. Because the math is universal, the same formulas apply whether you measure in meters or feet. The calculator keeps the full precision of pi so circles, ellipses, and sectors stay accurate.
Square Units and Conversions
Area is always measured in square units, and the conversions are not the same as length. One meter is 100 centimeters, but one square meter is 10,000 square centimeters because both dimensions scale. One square meter is also about 10.76 square feet. The calculator shows your result in your chosen unit and converts it to square meters, square centimeters, and square feet so you can use whichever fits your project.
Choosing the Right Shape
Most real surfaces approximate one of the ten shapes here. A wall or floor is usually a rectangle, a round table is a circle, a gable end is a triangle, and a garden bed might be an ellipse or a trapezoid. For anything irregular, split it into parts, calculate each area, and add them together. An L-shaped room, for example, is simply two rectangles combined.
Tips & Recommendations
Break a complex outline into simple shapes, calculate each area in the same unit, then add them up for the total.
Every dimension of one shape must use the same unit. Convert before you enter values, since the area is that unit squared.
The radius is half the diameter. Measure across the widest point of a circle and divide by two before entering it.
One square meter is 10,000 square cm, not 100. Area conversions square the length factor, so let the tool convert for you.
Frequently Asked Questions
Which shapes can this area calculator handle?
It calculates the area of ten common 2D shapes: square, rectangle, triangle, circle, parallelogram, trapezoid, ellipse, rhombus, circle sector, and regular polygon. Select a shape and the calculator shows exactly the dimensions it needs, then returns the area in your chosen unit squared along with conversions to other units.
How many square centimeters are in a square meter?
One square meter equals 10,000 square centimeters, not 100. This is because area scales with the square of the length: 100 cm times 100 cm equals 10,000 square cm. The same logic means one square meter is about 10.76 square feet. This calculator handles these conversions automatically so you never multiply by the wrong factor.
How do I calculate the area of an irregular shape?
Break the shape into simpler pieces whose areas you can calculate, then add them together. An L-shaped room, for example, splits into two rectangles. A house gable splits into a rectangle and a triangle. Calculate each part in the same unit and sum the results. For curved or truly irregular outlines, approximate with shapes that fit closely.
What is the radius?
The radius is the distance from the center of a circle to its edge, which is exactly half the diameter. If you only know the diameter, divide it by two to get the radius. For a circle or a circle sector, the radius is the key measurement, so measure across the full width and halve it before entering the value.
Do all dimensions need to be in the same unit?
Yes. Every length you enter for one shape must use the same unit, because the area is that unit squared. If you mix centimeters and meters, the result will be wrong. Convert everything to a single unit first, enter the values, and pick that unit in the calculator. Angles for the sector are always in degrees and the polygon side count is just a number.
What is the formula for the area of a circle?
The area of a circle is pi times the radius squared, written as π × r². For a radius of 3, that gives about 28.27 square units. The calculator uses the full precision of pi, and for a circle sector it scales this by the fraction of the full 360 degrees that the sector covers.
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