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Right Trapezoid Calculator | Solve Geometry From Bases and Height

Calculate the area, slant side, perimeter, diagonals and angles of a right trapezoid from its bases and height, with the Pythagorean step for the slant side shown. The complete solution for trapezoid problems.

Last updated: July 2026 · Free · No sign-up required

Results

Enter values above and click Calculate to see your result instantly.

Quick reference

Bases a, bHeight hAreaSlant side
10, 63245
12, 85506.40
20, 14813610
9, 94364 (rectangle)

info Right Trapezoid Calculator

Free math calculator — enter your numbers and get an instant, accurate result.

info Private by design

Everything runs locally in your browser. No uploads, no accounts, no tracking.

info Works everywhere

Fully responsive and mobile-friendly — calculate on any device, any time.

info Educational

Includes the formula and step-by-step explanation so you understand the math, not just the answer.

Interpretation guide

PropertyWhat it tells you
Two right anglesBoth sit on the perpendicular leg (the height)
Slant sideHypotenuse of the right triangle with legs h and (a − b)
Acute angleAlways at the long base, next to the slant side
a = bThe shape degenerates into a rectangle (slant = h)

lightbulb Worked example

Let's say you are using the Right Trapezoid Calculator. Calculates the area, slant side, perimeter, diagonals and angles of a right trapezoid from its two parallel bases and height. Enter the values that match your situation into the input fields and press calculate — using realistic numbers makes the result directly useful for you.

Result: The calculator instantly applies the formula Area = (a + b) ÷ 2 × h; slant c = √((a − b)² + h²); perimeter = a + b + h + c and returns the result with appropriate precision.

What this means: Read the result in the context of what you are measuring. The step-by-step breakdown lets you confirm the math and understand which input most affects the outcome.

Formula & methodology

Formula: Area = (a + b) ÷ 2 × h; slant c = √((a − b)² + h²); perimeter = a + b + h + c

The Right Trapezoid Calculator is built on a well-established calculation method. It uses the formula Area = (a + b) ÷ 2 × h; slant c = √((a − b)² + h²); perimeter = a + b + h + c to turn your inputs into a reliable result. Calculates the area, slant side, perimeter, diagonals and angles of a right trapezoid from its two parallel bases and height. The steps are shown on the page so you can follow the reasoning from input to output.

  1. Enter the long base a and short base b — the two parallel sides.
  2. Enter the height h, which in a right trapezoid is also the perpendicular leg.
  3. The slant side is found with the Pythagorean theorem on legs h and (a − b).
  4. Read off area, perimeter, diagonals and both non-right angles.

Worked example: bases 10 and 6 with height 3 → area = (10 + 6)/2 × 3 = 24, slant side = √(4² + 3²) = 5, perimeter = 10 + 6 + 3 + 5 = 24, acute angle = atan(3/4) = 36.87°.

Authoritative source: Wolfram MathWorld

Frequently asked questions

What is a right trapezoid?
The Right Trapezoid Calculator is free, private, and accurate: it runs entirely in your browser (no uploads, no accounts), applies the standard calculation, and explains each step so you can verify the result. Calculates the area, slant side, perimeter, diagonals and angles of a right trapezoid from its two parallel bases and height. There is no limit on usage, and it works on any device.
How do you find the area of a right trapezoid?
Enter the required values into the input fields and press the calculate button. The tool applies the formula Area = (a + b) ÷ 2 × h; slant c = √((a − b)² + h²); perimeter = a + b + h + c and returns the result with a short explanation of each step, so you can check the working yourself.
How do you find the slant side of a right trapezoid?
Use the Pythagorean theorem with the height and the base difference: slant = √(height² + (base₁ − base₂)²). For a trapezoid with bases 10 and 6 and height 8, the slant is √(64 + 16) = √80 ≈ 8.94. The calculator derives it from the two bases and the height, then uses it for the perimeter.
Can a right trapezoid have equal bases?
If the bases are equal, the shape is a rectangle — a trapezoid with one pair of parallel sides degenerates into a parallelogram (rectangle when right) when the parallel sides match. The calculator handles this gracefully: the slant side becomes the height, and the formulas still work. The area formula (base₁ + base₂) ÷ 2 × height reduces to base × height.
What are the angles of a right trapezoid?
A right trapezoid has two 90° angles by definition — the right angles at the legs that are perpendicular to the bases. The other two angles are supplementary and depend on the base lengths: with bases 10 and 6 and height 8, one acute angle is about 63.4° and the other obtuse is 116.6°. The calculator returns all four angles.
How do I find the angles of a trapezoid?
Co-interior angles between the parallel sides always sum to 180°. A right trapezoid fixes two of them at 90°, so only one angle needs computing: with parallel sides 10 and 6 and height 5, the slant leg rises over a run of 4, making the acute angle tan⁻¹(5/4) = 51.3° and its partner 128.7°. All four angles of any trapezoid total 360°.
What does the Right Trapezoid Calculator do?
Calculates the area, slant side, perimeter, diagonals and angles of a right trapezoid from its two parallel bases and height. The calculator takes your inputs, applies the standard calculation, and returns a clear result so you can make an informed decision without doing the math by hand.
What formula does the Right Trapezoid Calculator use?
The Right Trapezoid Calculator applies the standard formula: Area = (a + b) ÷ 2 × h; slant c = √((a − b)² + h²); perimeter = a + b + h + c. The tool walks through each step of the calculation so you can verify the numbers yourself.
Is the Right Trapezoid Calculator free and private?
Yes — the Right Trapezoid Calculator. There is no sign-up, no paywall, no trial, and no limit on how many calculations you can run. CalcaTools covers its costs with non-intrusive display advertising, so the calculator itself never asks for payment or restricts any feature.
How accurate is the Right Trapezoid Calculator?
The Right Trapezoid Calculator applies the standard formula: Area = (a + b) ÷ 2 × h; slant c = √((a − b)² + h²); perimeter = a + b + h + c. It is tested against published worked examples before launch and uses native double-precision arithmetic, so results are accurate to typical precision for the values you enter — with no intermediate rounding that could distort the answer.

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