Surface area units from microscopic scientific scales through land surveying and geographic areas.
All factors come from the central conversion registry.
| Unit | Symbol | System | Definition |
|---|---|---|---|
| Square Millimeter | mm² | SI | 1 mm² = 10⁻⁶ m² |
| Square Centimeter | cm² | SI | 1 cm² = 10⁻⁴ m² |
| Barn | b | Scientific | 1 b = 10⁻²⁸ m² |
| Square Inch | in² | International | 1 in² = 0.00064516 m² |
| Square Foot | ft² | International | 1 ft² = 0.09290304 m² |
| Square Meter | m² | SI | 1 m² = 1 m² |
| Square Yard | yd² | International | 1 yd² = 0.83612736 m² |
| Square Rod | rd² | Survey/Imperial | 1 square rod = 25.29285264 m² |
| Are | a | Metric | 1 a = 100 m² |
| Square Chain | ch² | Survey/Imperial | 1 square chain = 404.68564224 m² |
| Rood | rood | Imperial historical | 1 rood = 1,011.7141056 m² |
| Acre | acre | International | 1 acre = 4046.8564224 m² |
| Hectare | ha | Metric | 1 ha = 10,000 m² |
| Square Kilometer | km² | SI | 1 km² = 1,000,000 m² |
| Square Mile | mi² | International | 1 mi² = 2,589,988.110336 m² |
Area scales the underlying length factor twice. That is why converting square feet to square meters uses the square of the foot-to-meter relationship rather than the ordinary linear factor.
The interactive calculator, reference table and indexed pair pages all read from the same conversion registry, so unit definitions and formulas stay synchronized.