Trapezoid Area Calculator
Find the area and midline of a trapezoid from its two bases and height.
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Input
Enter the top base, bottom base, and height of a trapezoid to calculate its area and midline length.
length
length
length
Result
Area
35area
Midline (a+b)÷2
7
Base sum
14
Calculated as area equals (top base plus bottom base) times height divided by two.
Keep length units consistent. The area is in those units squared.
How it works
- The area of a trapezoid equals the sum of the two bases times the height, divided by two. Area equals (top base plus bottom base) times height divided by two.
- It does not matter which base is longer. As long as the sum of the bases is the same, the area is the same.
- The midline connects the midpoints of the two parallel sides. Its length equals (top base plus bottom base) divided by two, and the area also equals midline times height.
- The height is the perpendicular distance between the two parallel bases, not the length of a slanted side.
- Keep the units of the lengths consistent. The area is given in those units squared.
Frequently asked questions
- What formula does the trapezoid area calculator use?
- It uses area = (top base + bottom base) × height ÷ 2. For example, a top base of 4 cm, bottom base of 6 cm, and height of 5 cm give (4 + 6) × 5 ÷ 2 = 25 cm².
- How is this different from a rectangle calculation?
- A rectangle is height × width, but a trapezoid has two bases of different lengths, so it uses (top base + bottom base) × height ÷ 2. When the two bases are equal, the result matches a rectangle.
- What is the midline and how is it found?
- The midline connects the midpoints of the two bases and has length (top base + bottom base) ÷ 2. The area can also be found as midline × height. Note the height is the perpendicular distance between the bases, not the length of a slanted side.
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