mathematics calculator
Area Of A Trapezoid Calculator
Calculate trapezoid area from two parallel base lengths and their perpendicular height.
Area Of A Trapezoid Calculator
Trapezoid area
Enter both parallel bases and their perpendicular separation.
Use the same length unit for both bases and height. Area is returned in that unit squared.
Formula version 1.0.0
How to use this calculator
- Enter the two positive parallel base lengths.
- Enter the perpendicular height between them.
- Use one length unit for all inputs.
- Calculate area and review the average-base step.
Symbols and units
| Symbol | Meaning | Unit or domain |
|---|---|---|
a,b | Parallel base lengths | length |
h | Perpendicular height | length |
A | Trapezoid area | square length |
Checked examples
Unequal bases
Inputs: Bases 8 and 6; height 6
Calculation: A=(8+6)÷2×6
Result: 42 square units
The average base is seven and is multiplied by height.
Check: trapezoid-area-core.test.ts
Equal bases
Inputs: Bases 5 and 5; height 2
Calculation: A=(5+5)÷2×2
Result: 10 square units
With equal bases, the formula reduces to rectangle area.
Check: trapezoid-area-core.test.ts
Assumptions, rounding, and limits
- The two stated sides are parallel.
- Height is perpendicular to both bases.
- Inputs are positive and use one unit.
- The shape is planar and Euclidean.
Frequently asked questions
Can I use a slanted side as height?
Only if it is perpendicular to the parallel bases; otherwise find the perpendicular distance.
Does base order matter?
No. Swapping the two bases gives the same area.
What if the bases are equal?
The calculation correctly becomes base times height.
Sources and review
- OpenStax: Area — Trapezoid area
- OpenStax: Use Properties of Rectangles, Triangles, and Trapezoids — Parallel bases and height
- Formula version
- trapezoid.area@1.0.0
- Formula review
- Equatara formula review
- Editorial review
- Equatara editorial review
- Last verified
- 2026-10-25
- Applicability
- Planar trapezoid with two parallel bases and perpendicular height.
- Next review
- On material formula/source change, or by 2028-10-25.
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