Calculator Inputs
The page uses a single clean content flow. The form below uses a responsive 3-column, 2-column, and 1-column arrangement.
Example Data Table
| Example | Top Base | Bottom Base | Height | Average Base | Area |
|---|---|---|---|---|---|
| Small classroom shape | 6 m | 10 m | 4 m | 8 m | 32 m² |
| Garden bed | 8 ft | 14 ft | 5 ft | 11 ft | 55 ft² |
| Ramp surface | 3.5 m | 6.5 m | 2.4 m | 5 m | 12 m² |
| Plot section | 12 cm | 18 cm | 9 cm | 15 cm | 135 cm² |
Formula Used
Trapezoid Area Formula
Area = ((a + b) / 2) × h
Where a is the top base, b is the bottom base, and h is the perpendicular height.
Average Base: (a + b) / 2
Area Per Unit Height: Equal to the average base.
Optional Perimeter: a + b + left leg + right leg
The calculator focuses on area first, then adds supporting geometry metrics when optional side lengths are provided.
How to Use This Calculator
- Enter the top base of the trapezoid.
- Enter the bottom base of the trapezoid.
- Enter the perpendicular height between the parallel sides.
- Add left and right leg values only if you want perimeter details.
- Type a unit label like cm, m, or ft.
- Select how many decimal places you want.
- Press the calculate button to see the result above the form.
- Use the CSV or PDF buttons to export the computed values.
FAQs
1) What is a trapezoid?
A trapezoid is a quadrilateral with one pair of parallel sides. Those parallel sides are called bases, and the vertical distance between them is the height.
2) What values are required for area?
You only need the top base, bottom base, and perpendicular height. The leg lengths are optional and are used only for extra metrics like perimeter.
3) Why is the average base used?
A trapezoid’s area equals the height multiplied by the average of its parallel sides. That average represents the effective width across the shape.
4) Can this calculator find perimeter too?
Yes. Enter both leg lengths in addition to the two bases. The calculator will then add all four sides and display the perimeter.
5) Does the unit affect the formula?
No. The formula stays the same for every unit system. The unit label only changes how the result is displayed, such as cm², m², or ft².
6) What does the Plotly graph show?
The graph shows how area changes as height increases while your two base values stay fixed. It helps visualize the direct relationship between height and area.
7) Can I use decimal values?
Yes. The inputs support decimals, which is useful for measured objects, site plans, and practical geometry problems that do not use whole numbers.
8) When should I provide leg lengths?
Provide them when you also want perimeter information or a quick isosceles check. They are not needed for the area calculation itself.