Trapezoid Calculator
Calculate area, perimeter, median, and angles of a trapezoid from its parallel sides and height.
Dimensions
Updates as you typeMode
What do you want to solve for? ?
Target area
—
cm²
Units ?
Shape ?
Parallel sides & height
Side a (top) ?
—
cm
Side b (bottom) ?
—
cm
Height (h) ?
—
cm
Slant sides (optional — unlocks perimeter & angles) ?
Left leg (c)
—
cm
Right leg (d)
—
cm
Diagram
Scales with your inputsFormula
A
=
½(a + b) × h
,
m
=
(a + b) / 2
,
P
=
a + b + c + d
- A
- Area of the trapezoid
- a, b
- Parallel sides — a the shorter top, b the longer bottom
- h
- Perpendicular height between a and b
- m
- Median — the segment halfway up, equal to the average of a and b
- c, d
- Slant sides (legs) — left and right
- P
- Perimeter (sum of all four sides)
- α, β
- Base angles: α = arcsin(h / c), β = arcsin(h / d)
Worked example — your numbers
- Sum of parallel sides: a + b = —
- Median m = (a + b) / 2 = —
- Area A = ½(a + b) × h = —
- Perimeter P = a + b + c + d = —
- Left angle α = arcsin(h / c) = —
- Right angle β = arcsin(h / d) = —
The trapezoid is the most general of the four-sided shapes with at least one pair of parallel sides. When a = b it becomes a parallelogram; when the two slant sides are equal it is isosceles (mirror-symmetric); when one slant side equals h it is a right trapezoid (one pair of 90° corners). Angles require the slant sides — perimeter does too.