Isosceles Trapezoid Calculator
Area, perimeter, legs, diagonals and base angles.
Enter your values
Enter the longer base a you are working with.
Enter the shorter base b you are working with.
Enter the height you are working with.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Area
- 32
- Perimeter
- 24.9443
- Leg length
- 4.4721
- Diagonal
- 8.9443
- Base angle
- 63.43°
- Top angle
- 116.57°
Quick answer
An isosceles trapezoid has equal legs and equal base angles; its area is the average of the two bases times the height.
A = (a + b) ÷ 2 × h
At a glance
| What it does | Area, perimeter, legs, diagonals and base angles. |
|---|---|
| Category | Math |
| Inputs needed | Longer base a, Shorter base b, Height |
| Main output | Area |
| Formula | A = (a + b) ÷ 2 × h |
| Cost | Free — no sign-up, no download |
How to use the Isosceles Trapezoid Calculator
- 1Enter both parallel base lengths.
- 2Enter the perpendicular height.
- 3Read area, legs, diagonals and angles.
Inputs explained
- Longer base a
- Enter the longer base a you are working with.
- Shorter base b
- Enter the shorter base b you are working with.
- Height
- Enter the height you are working with.
Worked example
Using the values the calculator loads with:
Inputs
- Longer base a10
- Shorter base b6
- Height4
Results
- Area32
- Perimeter24.9443
- Leg length4.4721
- Diagonal8.9443
- Base angle63.43°
- Top angle116.57°
Frequently asked questions
Are the diagonals of an isosceles trapezoid equal?
Yes — equal diagonals are one of the defining properties of an isosceles trapezoid.
How do I find the leg length?
Half the base difference is the horizontal offset; the leg is the hypotenuse of that offset and the height.
What do I need to enter into the Isosceles Trapezoid Calculator?
Just 3 values: longer base a, shorter base b, height. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Isosceles Trapezoid Calculator work out the answer?
An isosceles trapezoid has equal legs and equal base angles; its area is the average of the two bases times the height. It applies the formula A = (a + b) ÷ 2 × h and shows the working so you can check each step by hand.
Is the Isosceles Trapezoid Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.