Calculator Input
Use coordinates for highest accuracy. Use sides plus one diagonal when corner coordinates are unavailable.
Formula Used
1) Coordinate Method
Shoelace formula:
Area = |(x1y2 + x2y3 + x3y4 + x4y1) - (y1x2 + y2x3 + y3x4 + y4x1)| / 2
2) Four Sides + Diagonal Method
Step A: Split the uneven shape into triangles ABC and ACD using diagonal AC.
Step B: Apply Heron’s formula to each triangle.
s = (a + b + c) / 2Triangle Area = √(s(s-a)(s-b)(s-c))Total Area = Area(ABC) + Area(ACD)
3) Helpful Supporting Values
Perimeter: Add all four side lengths.
Centroid: Derived from polygon coordinates, useful for plotting and layout checks.
How to Use This Calculator
- Select the calculation method that matches your measurements.
- Choose the unit used for all entered values.
- For coordinates, enter four corner points in boundary order.
- For side-and-diagonal mode, enter AB, BC, CD, DA, and AC.
- Set your preferred decimal precision.
- Click Calculate Area to show the result above the form.
- Review the plotted outline, conversions, and detailed output table.
- Use the CSV or PDF buttons to save your result.
Example Data Table
| Example | Method | Input Data | Computed Area | Note |
|---|---|---|---|---|
| Plot A | Coordinates | (0,0), (8,1), (9,6), (1,5) | 39.00 m² | Good for surveyed points. |
| Plot B | Sides + Diagonal | AB=8, BC=5, CD=8, DA=6, AC=9 | 43.71 m² | Useful when coordinates are unavailable. |
| Plot C | Coordinates | (0,0), (12,0), (11,7), (1,6) | 71.50 ft² | Works for uneven four-corner layouts. |
FAQs
1) What is an uneven square in this calculator?
It means an irregular four-corner shape that is not a perfect square. The sides or angles may differ, but the figure still has four boundary points.
2) Which method gives the best accuracy?
The coordinate method is usually most accurate because it uses actual corner positions. It works especially well for land plots, floor plans, and measured site layouts.
3) Why does the diagonal method need one diagonal?
A diagonal splits the shape into two triangles. Once each triangle is known, Heron’s formula can calculate both areas and then combine them into one total.
4) Can I use feet, meters, yards, centimeters, or inches?
Yes. Enter your measurements in one consistent unit, and the calculator will also show converted area and perimeter values in the other supported units.
5) Why am I getting a self-intersection warning?
That warning appears when the entered corner order crosses over itself. Re-enter the points in clockwise or counterclockwise order around the outer boundary.
6) Can this help with land, flooring, or paving estimates?
Yes. It is useful for many practical jobs, including irregular plots, patios, rooms, paving sections, and other four-corner spaces that are not perfectly square.
7) What do CSV and PDF downloads include?
They include the calculation method, area, perimeter, centroid, and key measurement values. This makes it easier to save, share, or document your work.
8) How can I improve measurement quality?
Measure carefully, keep units consistent, verify point order, and recheck the diagonal if you use the split-triangle method. Better field measurements produce better area estimates.