Geometry & Shapes
Trapezoid Calculator
Trapezoid: it uses area = ½ × (a + b) × height from the two parallel sides and the height you enter. Worked through below with real figures, and the calculator repeats the working on your own inputs — free, on-device, instant.
Trapezoid Calculator helps you find the area of a trapezoid. Enter your parallel side a, parallel side b and height and it returns the area instantly, right in your browser with nothing uploaded.
About this calculator
It matters whenever a shape has to be measured, cut, covered or compared and the geometry has to be right first. The governing relationship: It uses area = ½ × (a + b) × height from the two parallel sides and the height you enter. See it on real numbers: Parallel sides 6 and 10, height 4: area = ½ × (6+10) × 4 = 32 . The calculator above applies the same steps to whatever you enter — computed locally, nothing sent anywhere.
How to use
- Enter the first parallel side (a).
- Enter the second parallel side (b).
- Enter the perpendicular height.
- Press Calculate to find the trapezoid's area.
Why use Trapezoid Calculator
Fast
Calculations run in your browser. No round trip to a server.
Private
Your inputs never leave your device. Nothing is uploaded.
Free
No signup, no paywall, no ads-in-results, no watermarks.
Accurate
Uses standard formulas where applicable; check critical results before relying on them.
Mobile-ready
Optimised for phones, tablets, and desktops alike.
Transparent
Honest disclaimers wherever browser limits or regional rules apply.
Common uses
Use it when comparing two shapes' areas
Use it for flooring and surface estimates
Use it when sizing a room or panel
Use it when teaching shape area
Use it for craft and woodworking projects
Use it when checking a homework answer
Technical notes
Trapezoid Calculator uses area = ½ × (a + b) × height from the two parallel sides and the height you enter.
Results assume exact, idealised shapes; real-world measurement error is not included.
Nothing you type is uploaded — the calculation happens entirely on your device.
FAQ
How is the area of a trapezoid calculated?
The area is the average of the two parallel sides multiplied by the perpendicular height: ((a + b) / 2) times h.
Which sides are a and b?
Sides a and b are the two parallel sides; the height is the perpendicular distance between them.
Does it matter which parallel side I enter first?
No. Adding a and b gives the same result regardless of order.
Does the Trapezoid Calculator send my data to a server?
No. The Trapezoid Calculator runs entirely in your browser, so nothing you enter is uploaded, stored, or shared.
Worked example
Parallel sides 6 and 10, height 4: area = ½ × (6+10) × 4 = 32.