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Area Calculator

Calculate the area and perimeter of common geometric shapes like rectangles, squares, circles, triangles, trapezoids, parallelograms, ellipses, and sectors.

CalculatorHow to CalculateFormulas & ExamplesFAQs

Select a shape and enter dimensions to calculate.

Dimension Specifications

Dimension Guide
LengthWidth

Ready to Calculate

Select a geometric shape, enter your dimensions, and click Calculate to see results.

Formula Details

Select a shape above to display its corresponding geometry formula and variables, or browse the specific calculations below:

Calculation Example

Worked Example
Scenario

Room Flooring: Calculate the area and perimeter of a rectangular living room flooring measuring 18 feet long by 14 feet wide for ordering hardwood planks and baseboards.

Calculation Steps
  1. 1.Select Rectangle shape and enter dimensions: Length = 18 ft, Width = 14 ft.
    rectLength = 18 ft, rectWidth = 14 ft
  2. 2.Compute net floor area.
    Area = 18 ft × 14 ft = 252.00 ft² (equivalent to 28.00 yd² or 23.41 m²)
  3. 3.Compute outer perimeter for baseboard layout.
    Perimeter = 2 × (18 ft + 14 ft) = 64.00 ft (equivalent to 21.33 yd or 19.51 m)
Final Quantity NeededArea: 252.00 ft², Perimeter: 64.00 ft
Worked Example
Scenario

Circular Garden: Determine the area and outer circumference of a circular garden bed with a radius of 3.5 meters for sod roll ordering and border edging.

Calculation Steps
  1. 1.Select Circle shape and enter dimensions: Radius = 3.5 m.
    circleRadius = 3.5 m
  2. 2.Compute garden lawn area.
    Area = π × (3.5 m)² ≈ 38.48 m² (equivalent to 414.25 ft²)
  3. 3.Compute garden outer circumference for border edging.
    Circumference = 2 × π × 3.5 m ≈ 21.99 m (equivalent to 72.15 ft)
Final Quantity NeededArea: 38.48 m², Circumference: 21.99 m
Worked Example
Scenario

Concrete Slab: Calculate the surface area of a trapezoidal concrete driveway slab that has a top base of 10 feet, bottom base of 16 feet, and height of 24 feet.

Calculation Steps
  1. 1.Select Trapezoid shape and enter dimensions: Top Base (a) = 10 ft, Bottom Base (b) = 16 ft, Height (h) = 24 ft.
    a = 10 ft, b = 16 ft, h = 24 ft
  2. 2.Compute concrete surface area.
    Area = ((10 ft + 16 ft) × 24 ft) / 2 = (26 × 24) / 2 = 312.00 ft² (equivalent to 34.67 yd² or 28.99 m²)
  3. 3.Note: Perimeter is underdetermined because the diagonal slant lengths are not provided.
    Perimeter = N/A
Final Quantity NeededArea: 312.00 ft² (Perimeter not applicable)

How to Use

Follow these simple steps to calculate the area, perimeter, and equivalent units for your design or construction project:

  1. Select the shape: Click on one of the 8 shape icons at the top (Rectangle, Square, Circle, Triangle, Trapezoid, Parallelogram, Ellipse, or Sector).
  2. Enter dimensions: Supply the required dimensions for the chosen shape in the dynamic fields.
  3. Choose the preferred unit system: Toggle between Imperial (ft/in/yd) and Metric (m/cm/mm) to match your measurements.
  4. Click Calculate: Click the Calculate button to process the dimensions.
  5. Review the results: View the calculated Area and Perimeter (if applicable) alongside a list of equivalent conversions in other units.
  6. Utilize values: Click **Reset** if you want to clear fields and start a new geometry calculation.

Frequently Asked Questions

How do I calculate the area of a rectangle?
To find the area of a rectangle, multiply its length by its width (Area = Length × Width). Ensure both dimensions are in the same unit. For instance, a rectangle measuring 10 meters by 5 meters has an area of 50 square meters (m²).
What is the difference between area and perimeter?
Area measures the total two-dimensional space enclosed inside a geometric shape (expressed in square units like ft² or m²). Perimeter measures the total distance around the outer boundary of the shape (expressed in linear units like ft or m).
Which unit should I use?
Choose the unit system that matches your construction documents or material supplier. Standard metric units include millimeters (mm) for mechanical/detailed assemblies, centimeters (cm) for architectural detailing, and meters (m) for site plans. Imperial units include inches (in) for sizing, feet (ft) for framing/layouts, and yards (yd) for earthwork and concrete ordering.
Can I switch between Metric and Imperial?
Yes, you can toggle between Imperial (in, ft, yd) and Metric (mm, cm, m) systems at the top of the estimator card. All fields, labels, placeholders, and results will automatically convert instantly.
How accurate are the calculations?
The calculations are mathematically exact based on standard geometric formulas. For the ellipse perimeter, we utilize Ramanujan's first approximation which is highly accurate and provides precision suitable for construction and landscaping design.
Why are some shapes missing a perimeter calculation?
Shapes like the triangle, trapezoid, and parallelogram require additional boundary side lengths or angle measurements to determine their perimeter. Since this calculator collects only the base and height dimensions necessary for area estimation, their perimeters are mathematically underdetermined and thus marked as not applicable.

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Disclaimer

Calculations are estimates based on the values you enter and standard engineering formulas. Results are intended for planning and estimation only. Always verify critical measurements, specifications, and local building requirements before purchasing materials or beginning construction.