Use this free geometry calculator to find the area of common 2D figures. Choose a shape, enter dimensions, and click calculate.
What is area in geometry?
Area is the amount of surface inside a two-dimensional boundary. If a shape is drawn on paper, area tells you how much paper the shape covers. It is measured in square units, such as square centimeters (cm²), square meters (m²), or square feet (ft²).
An area of a figure calculator helps you skip repetitive arithmetic and avoid formula mistakes. It is useful for students, teachers, engineers, designers, builders, and anyone solving day-to-day measurement problems.
How to use this area of a figure calculator
- Select the figure you want to calculate.
- Enter all required dimensions (such as base, height, radius, or diagonals).
- Optionally enter a unit like cm or m for cleaner output.
- Click Calculate Area.
- Read the result, formula, and substitution shown below the form.
Area formulas included
Basic shapes
- Rectangle: A = length × width
- Square: A = side²
- Triangle: A = ½ × base × height
- Circle: A = πr²
Intermediate shapes
- Parallelogram: A = base × height
- Trapezoid: A = ½ × (base₁ + base₂) × height
- Ellipse: A = πab (a and b are semi-axes)
- Rhombus: A = ½ × diagonal₁ × diagonal₂
Special figures
- Sector of a circle: A = (θ/360) × πr²
- Regular polygon: A = ½ × perimeter × apothem
Worked examples
Example 1: Rectangle
If length = 10 and width = 4, then area = 10 × 4 = 40 square units.
Example 2: Circle
If radius = 7, then area = π × 7² = 49π ≈ 153.94 square units.
Example 3: Trapezoid
If base₁ = 8, base₂ = 14, and height = 6, then area = ½ × (8 + 14) × 6 = 66 square units.
Common mistakes to avoid
- Using diameter instead of radius in circle area.
- Forgetting the ½ factor in triangles, trapezoids, and rhombus formulas.
- Mixing units (for example, one side in cm and another in m).
- Using slanted side length instead of perpendicular height for triangles and parallelograms.
- Entering negative or zero values for dimensions.
Area units and conversions
Always keep units consistent before calculating. Quick references:
- 1 m² = 10,000 cm²
- 1 ft² = 144 in²
- 1 hectare = 10,000 m²
- 1 acre ≈ 4046.86 m²
Real-world uses of area calculations
- Estimating paint needed for walls and ceilings
- Calculating flooring, tiles, carpet, and roofing materials
- Planning gardens and agricultural land sections
- Designing signs, posters, and printed layouts
- Solving school and exam geometry problems faster
Final tip
If a figure is complex, break it into simple shapes (rectangles, triangles, and circles), calculate each area separately, then add or subtract as needed. This approach works for most composite shapes and can dramatically reduce errors.