Trapezoid Area Formula
The area of a trapezoid is calculated by adding the lengths of its two parallel sides, multiplying the result by the perpendicular height, and dividing by two.
Area = (Parallel Side 1 + Parallel Side 2) × Height ÷ 2
The two parallel sides are sometimes called the bases of the trapezoid. The height is the perpendicular distance between those parallel sides. The height is not the length of either sloping side.
How to Calculate Trapezoidal Land Area
- Measure the first parallel side of the plot.
- Measure the second parallel side of the plot.
- Measure the perpendicular height between the two parallel sides.
- Make sure all three measurements use the same length unit.
- Add the two parallel sides, multiply by the height, and divide by two.
Example: 20 m, 30 m and 10 m
Suppose a trapezoidal plot has parallel sides of 20 metres and 30 metres, with a perpendicular height of 10 metres.
Area = (20 + 30) × 10 ÷ 2
Area = 250 square metres
Using the Trapezoid Calculator for Land Measurement
This calculator is useful when a land plot can reasonably be represented as a trapezoid and two opposite sides are parallel. Enter the two parallel-side measurements and the perpendicular height to calculate the geometric area.
The geometric area calculated here is different from local revenue or customary land-unit conversions. If you need the result in a local land unit such as bigha, biswa, or another regional unit, use a conversion source appropriate to the relevant location and measurement convention.
Common Measurement Mistakes
- Using a sloping side as the height instead of the perpendicular distance between the parallel sides.
- Mixing feet with metres or another length unit.
- Confusing feet (ft) with square feet (ft²).
- Treating two non-parallel sides as the parallel sides.
- Assuming the geometric area automatically represents a local revenue-record measurement.
When Not to Use a Trapezoid Area Calculator
If the plot has equal length and width measurements forming a rectangle, use the Rectangle Area Calculator instead.
If the plot can reasonably be represented as a triangle, use the Triangle Area Calculator.
If the plot boundary is irregular or its parallel sides and perpendicular height cannot be reliably measured, this simple trapezoid formula should not be used.
Frequently Asked Questions
What is the formula for trapezoid area?
The formula is Area = (Parallel Side 1 + Parallel Side 2) × Height ÷ 2.
What is the height of a trapezoid?
The height is the perpendicular distance between the two parallel sides. It is not necessarily the length of a sloping side.
Can I calculate trapezoid area in feet?
Yes. Enter both parallel sides and the height in feet, and the calculator can provide the result in square feet or another supported square-area unit.
Can this calculator calculate an irregular plot?
No. The trapezoid formula should only be used when the plot can reasonably be represented by a trapezoid with two parallel sides and a measurable perpendicular height.
Land Measurement Note
This calculator provides a geometric area calculation based on the measurements entered by the user. It does not determine legal ownership, cadastral boundaries, survey boundaries, or official revenue-record area.