Two bases and height
Base a + Base b + Height h
A = (a+b)h/2
Open calculator ↗GEOMETRY, ONE FIGURE AT A TIMETrapezoid.
Trapezoid.
Understand every measure.
Two parallel bases make the area simple. Four free tools, clear formulas and a little discovery along the way.
Find your calculator ↗FIGURE 102D / REFERENCE DRAWING
TRAPEZOIDNOT TO SCALE
THE CALCULATOR DESK
Start with what you know.
4 calculators available
Two bases and two legs
Base a + Base b + Leg c + Leg d
Δ = |a−b|; x = (c²−d²+Δ²)/(2Δ); h = √(c²−x²)
Open calculator ↗Isosceles trapezoid
Base a + Base b + Equal leg c
h = √[c²−(a−b)²/4]
Open calculator ↗Area to height
Area A + Base b + Other base c
h = 2A/(b+c)
Open calculator ↗MEET THE FIGURE
A trapezoid, explained.
A trapezoid here means a quadrilateral with at least one pair of parallel sides. These parallel sides are called bases. The non-parallel sides are called legs when there is just one parallel pair. Some textbooks use the exclusive “exactly one pair” definition instead.
Understand the properties ↗LOOK A LITTLE CLOSER
More than a formula.
Two congruent trapezoids can be arranged into a parallelogram that explains the area formula.
Equal bases with arbitrary legs do not uniquely determine a height. The four-side tool rejects that ambiguous case.
Explore three geometry facts ↗These tools use ideal Euclidean geometry. Every input must use the same unit. Numerical results are rounded and do not replace measurement, specialist design or safety checks. See worked examples.