# Area Calculator – Calculate Area of Various Shapes

Calculate area by selecting a shape and entering your measurements in any metric or US customary unit. See the formulas to calculate the area for each shape below.

**Select a Shape:**

## Rectangle

## Square

## Border

## Trapezoid

## Parallelogram

## Triangle

## Circle

## Ellipse

## Sector

## Regular Polygon

## On this page:

- Area Calculator - Find Area
- How to Calculate Area
- Square Area Formula
- Rectangle Area Formula
- Border Area Formula
- Trapezoid Area Formula
- Parallelogram Area Formula
- Triangle Area Formula
- Circle Area Formula
- Ellipse Area Formula
- Sector Area Formula
- Regular Polygon Area Formula
- Irregular Polygons and Complex Shapes
- Difference Between Area and Surface Area
- Difference Between Area and Perimeter

## How to Calculate Area

Area is the space inside the perimeter/boundary of space, and its symbol is (A). It’s the size of a 2-dimensional surface and is measured in square units, for example, square feet.

Square feet can also be expressed as ft^{2} or sq. ft. Use our formulas to find the area of many shapes.

It’s essential to measure all lengths in the same unit of measure or convert all lengths to the same unit before calculating area. Try our length unit conversion calculators or area unit conversion calculators for converting between imperial and metric measurements.

Use the formulas below to calculate the area of many popular shapes.

### Square Area Formula

A = a^{2}

A = a × a

a = edge length

### Rectangle Area Formula

A = l × w

l = length

w = width

### Border Area Formula

A = (l1 × w1) – (l2 × l2)

l1 = outer length

w1 = outer width

l2 = inner length

w2 = inner width

### Trapezoid Area Formula

A = ^{1}/_{2}(a + b)h

a = base a

b = base b

h = height

### Parallelogram Area Formula

A = b × h

b = base

h = height

### Triangle Area Formula

s = ^{1}/_{2}(a + b + c)

A = s(s – a)(s – b)(s – c))

a = edge a

b = edge b

c = edge c

This formula is known as Heron’s formula. You can also use a simplified formula if the height of the triangle is known.

A = ^{1}/_{2}bh

b = edge b

h = height

### Circle Area Formula

A = πr^{2}

r = radius

If you know the circle’s diameter you can find the radius by dividing the diameter in half.

Did you know we also have a calculator to find the area of a circle?

### Ellipse Area Formula

A = πab

a = axis a

b = axis b

### Sector Area Formula

A = (θ ÷ 360)πr^{2}

r = radius

θ = angle

Learn more about sectors and see more detailed examples on our sector area calculator.

### Regular Polygon Area Formula

A = (a^{2} × n) ÷ (4 × tan(π ÷ n))

a = edge length

n = number of sides

### Irregular Polygons and Complex Shapes

The trick to finding the area of an irregular polygon or complex shape is to break the shape up into regular polygons such as triangles and squares first, then find the area of those shapes and add them together to find the total.

## Difference Between Area and Surface Area

You might be wondering how area is different from surface area. While area is the size of a two-dimensional plane, surface area is the size of the surface of a three-dimensional solid shape.

## Difference Between Area and Perimeter

So what is the difference between perimeter and area? Perimeter is the distance around a two-dimensional shape, while area is the size of the shape itself.

Of course, we have a perimeter calculator to help solve this length measurement.