Calculator Form
Example Data Table
| Shape | Example Inputs | Deduction | Allowance | Planned Area |
|---|---|---|---|---|
| Rectangle | Length 60 m, Width 40 m | 150 sq m | 5% | 2,362.50 sq m |
| Trapezoid | Side A 30 ft, Side B 18 ft, Height 22 ft | 28 sq ft | 8% | 540.00 sq ft |
| Irregular Polygon | (0,0), (25,0), (30,12), (10,20), (0,10) in m | 20 sq m | 3% | 432.60 sq m |
Formula Used
| Shape | Formula |
|---|---|
| Rectangle | Area = Length × Width |
| Triangle | Area = 0.5 × Base × Height |
| Circle | Area = π × Radius² |
| Trapezoid | Area = ((Side A + Side B) ÷ 2) × Height |
| Parallelogram | Area = Base × Height |
| Ellipse | Area = π × Semi-major Axis × Semi-minor Axis |
| Irregular Polygon | Area = Shoelace formula from ordered corner coordinates |
| Net Area | Net Area = Base Area - Deductions |
| Planned Area | Planned Area = Net Area × (1 + Allowance ÷ 100) |
How to Use This Calculator
- Select the site shape that best matches your plot or engineering layout.
- Choose the unit for your input dimensions, then enter the required measurements.
- For irregular land, enter boundary points in order using x,y coordinates.
- Add any deduction area for excluded zones such as setbacks, voids, or service strips.
- Enter an allowance percentage if you want a planning buffer over the net area.
- Click the calculate button to show results above the form, review the chart, and export CSV or PDF files.
FAQs
1. What shapes does this calculator support?
It supports rectangles, triangles, circles, trapezoids, parallelograms, ellipses, and irregular polygons from coordinate points. That covers many engineering site layouts, pads, lots, and surveyed boundaries.
2. Which units can I use for input?
You can enter values in meters, feet, or yards. The calculator then converts the planned area into square meters, square feet, square yards, acres, and hectares.
3. Why would I enter a deduction area?
Use deductions for excluded portions such as easements, pits, access corridors, utility zones, void spaces, or non-usable strips. This helps you move from gross area to net usable area.
4. What does the allowance percentage do?
Allowance adds a percentage over the net area. Teams often use it for planning reserve space, construction tolerance, landscaping overages, or early-stage estimation buffers.
5. How does the irregular polygon option work?
Enter site corner points in boundary order. The calculator applies the shoelace formula to those coordinates, making it useful for irregular surveyed parcels and compound outlines.
6. Does this calculator measure sloped ground area?
No. It calculates plan area from horizontal dimensions or coordinate points. For sloped ground, first convert to horizontal distance or use a separate surface area method.
7. Can I use the result in reports or estimates?
Yes. After calculation, you can download a CSV or PDF summary showing the selected shape, input values, area stages, converted outputs, and formula reference.
8. Why is planned area different from base area?
Base area comes from the raw geometry. Net area removes exclusions. Planned area then adds your percentage buffer, so it reflects a more practical figure for engineering planning.