Whether you're planning a flooring job, buying wall paint, planting a garden or solving geometry problems – accurate area calculations are essential. Every shape has its own formula, and forgetting the triangle when tiling or misjudging the circle for a lawn means buying too much or too little material. The area calculator gives you the correct result instantly for all common shapes.
Step by Step: How to Use the Area Calculator
- Select the shape: Choose the geometric shape: rectangle, square, triangle, circle, trapezoid or parallelogram.
- Enter the dimensions: Input the required measurements – for a rectangle enter length and width, for a circle the radius or diameter, for a triangle the base and height.
- Choose the unit: Work in metres (for rooms and gardens), centimetres (for smaller objects) or millimetres (for trade and technical work).
- Add a waste allowance: For building materials, a cutting waste allowance of 5–15% is recommended – the calculator offers this option directly.
- Add multiple areas: For complex room shapes, calculate each section individually and add the results together.
Practical Examples
Example 1 – Living room renovation: Rectangular room 5.4 × 3.8 m = 20.52 m² floor area. For laminate flooring with 10% waste: 20.52 × 1.10 = 22.57 m². In packs of 2.5 m² you need 10 packs – buy 10, not 9.
Example 2 – Circular garden pond: Diameter 3.6 m → radius 1.8 m. Area: π × 1.8² = π × 3.24 = 10.18 m². For a pond liner with 50 cm overlap all around: diameter + 1 m = 4.6 m liner needed.
Example 3 – Rendering a gable triangle: Triangular gable wall, base 8 m, height 3.5 m. Area: (8 × 3.5) / 2 = 14 m². For exterior render at 1.5 kg/m²: 14 × 1.5 = 21 kg of render required.
Area Formulas for All Shapes
Rectangle: A = a × b. Square: A = a². Triangle: A = (b × h) / 2. Circle: A = π × r². Trapezoid: A = (a+c)/2 × h. Example: living room 5 × 4 m = 20 m².
Frequently Asked Questions (FAQ)
How do I calculate the area of an L-shaped room?
Split the L-shape into two rectangles, calculate each separately and add them together. Alternatively, calculate the overall enclosing rectangle and subtract the missing corner. Both methods give the same result.
What is the difference between gross floor area and usable floor area?
Gross floor area is the geometrically calculated total area including walls. Usable floor area (net living space) subtracts wall thicknesses and accounts for sloped ceilings. Use net floor area for flooring materials; use gross floor area for screed and subfloor construction.
Why do I need more tiles than the pure floor area suggests?
Because of cutting waste at walls, corners and around obstacles like toilets or columns. As a rule of thumb: allow 5–8% extra for straight laying, 10–15% for diagonal laying. Smaller tile formats generally produce less waste.
