Square Meters Calculator

The square metre (symbol m², spelled square meter in US English) is the SI derived unit of area, defined as the area of a square whose sides measure exactly one metre. Adopted by the General Conference on Weights and Measures in 1960 and now used by every country in the world except the United States, Liberia and Myanmar, it is the unambiguous global standard for floor plans, building permits, real-estate listings, agricultural land records and engineering drawings.

In the United Kingdom, RICS-regulated estate agents quote Gross Internal Area (GIA) in m² on every property listing, and Approved Documents under the Building Regulations specify thermal performance and ventilation rates per square metre of floor area. In the European Union, the Energy Performance of Buildings Directive measures kWh per m² per year, and notary deeds across France, Germany, Italy, Spain, the Netherlands and Scandinavia describe property area in m² to two decimal places. Australia, New Zealand, South Africa, Canada and India (where it competes with the traditional “carpet area” in sq ft) all use m² for civic, commercial and industrial floor measurement.

This calculator is purpose-built around that reality. It accepts dimensions in millimetres, centimetres, metres, inches or feet, normalises everything to SI internally, and outputs the primary result in m² with full conversions to cm², mm², sq ft, sq yd, sq in, hectares, acres and km². Seven shapes cover virtually every real-world surface: rectangle (almost every room), circle (round patios, ponds), triangle (gable ends, attic floors), ellipse (oval features), trapezoid (sloped lots, gable walls), regular polygon (hexagonal pavers, octagonal gazebos) and annulus (ring paths, pool surrounds). Add as many sub-areas as you need — L-shaped rooms, multi-zone gardens, whole apartments — and the tool sums them automatically. Material extensions for weight (kg/m²) and cost (€/£/$ per m²) turn raw geometry into a procurement-ready budget in seconds.