Area in square units
Area measures a two-dimensional region and is expressed in square units. The main result uses the selected unit squared; the additional results convert that same area rather than recalculating with different dimensions.
When you know three triangle side lengths rather than a base and height, use the Triangle Calculator .
The formula
Each formula uses perpendicular measurements. Ellipse inputs a and b are semi-axes, or half the full lengths through its center. Area conversion squares the length factor: 1 ft² = (0.3048 m)² = 0.09290304 m².
Worked example
A rectangle 6 m long and 4 m wide covers 24 m², approximately 258.333850 ft². A trapezoid with parallel sides 6 m and 4 m and perpendicular height 3 m covers 15 m².
How to use this calculator
- Select the shape and a common length unit.
- Enter the visible dimensions; use perpendicular height and half-axis lengths where labeled.
- Calculate and read the selected square unit plus the converted areas.
Height is not always a side length
For a triangle, parallelogram, or trapezoid, height is the shortest distance perpendicular to the chosen base. A sloping edge can be longer than that distance and should not be substituted. If you know three triangle side lengths instead of a base and height, the separate triangle calculator uses Heron’s formula.
Measuring a circle or ellipse
A circle radius runs from the center to the edge. A measured diameter must be divided by two before entry. Likewise, ellipse semi-axes are half the major and minor diameters. Entering full diameters into radius or semi-axis fields produces an area four times too large. Both ellipse axes may be equal, in which case the region is a circle.
Combining regions and choosing units
Split a composite outline into nonoverlapping supported shapes and add their areas. Subtract openings separately and retain one square unit throughout. This geometry tool does not apply material waste, repetition counts, or pricing. For repeated rectangular room measurements with allowance and unit conversions, the square-footage calculator provides that more specific workflow.
Assumptions & limitations
What this calculation assumes
- Shapes are ideal, flat regions with strictly positive dimensions.
What to keep in mind
- No irregular polygon, perimeter, openings, or material allowance calculation.
Common questions
What is the difference between m and m²?
Meters measure a length; square meters measure an area. An area conversion uses the square of the length conversion factor.
Does the trapezoid need equal sloping sides?
No. The formula requires the two parallel sides and their perpendicular separation, not equal legs.