📐 Knowledge · Geometry

How to Calculate
Area

Formulas and free calculators for every shape — rectangle, triangle, circle, trapezoid, and more.

Area Calculator

Rectangle
Triangle
Circle
Trapezoid
Parallelogram
Ellipse
length (l) w
A = length × width
Area
50
10 × 5 = 50
Perimeter
30
2 × (l + w)
base (b) h
A = ½ × base × height
Area
24
½ × 8 × 6 = 24
r
A = π × r²
Area
153.94
π × 7² = 153.94
Circumference
43.98
2 × π × r
a b h
A = ½ × (a+b) × h
Area
32
½ × (6+10) × 4 = 32
base (b) h
A = base × height
Area
45
9 × 5 = 45
a b
A = π × a × b
Area
125.66
π × 8 × 5 = 125.66

Quick Reference — All Formulas

Square
A = side²
Rectangle
A = l × w
Triangle
A = ½ × b × h
Circle
A = π × r²
Trapezoid
A = ½(a+b) × h
Parallelogram
A = b × h
Ellipse
A = π × a × b
Rhombus
A = ½ × d₁ × d₂

Worked Examples

Room Floor

Rectangle 5m × 4m
A = 5 × 4
20 m²

Pizza

Circle, r = 15cm
A = π × 15²
706.9 cm²

Roof Section

Triangle b=8m, h=3m
A = ½ × 8 × 3
12 m²

Flower Bed

Ellipse a=3m, b=1.5m
A = π × 3 × 1.5
14.14 m²

More Knowledge Calculators

Frequently Asked Questions

What units should I use for area?
Area is always in squared units. If you measure in metres, area is in m². If you measure in centimetres, area is in cm². Make sure all measurements use the same unit before calculating.
How do I calculate the area of an irregular shape?
Break the shape into simpler shapes (rectangles, triangles, circles), calculate each area separately, then add or subtract as needed. This method works for any polygon or compound shape.
What is the area of a square?
A square is a special rectangle where all sides are equal, so Area = side × side = side². A 5m × 5m square has an area of 25m².