How to use this calculator
Enter the lengths of the two parallel sides and the perpendicular distance between them. Either parallel side can be a or b.
Formula
A = (a + b) × h ÷ 2
Worked example
Parallel sides of 8 m and 14 m with height 5 m give (8 + 14) × 5 ÷ 2 = 55 m².
Assumptions and limits
Only one pair of sides needs to be parallel. Sloping side lengths are not supplied, so perimeter cannot be inferred.
Frequently asked questions
Does it matter which parallel side is a?
No. Swapping the two parallel side lengths gives the same area.
What units should I use?
Choose your input unit, then enter every dimension in that unit. The result unit can be changed independently.
Does this include waste or material costs?
No. This is geometric area only. Add openings, overlap, cutting waste, prices and installation requirements separately.
Calculated locally; rounded only for display.