Field guide / 07—08
Metres, centimetres and square metres
Know when a length unit becomes an area unit.
Length and area differ
A metre (m) measures one direction; a square metre (m²) measures a surface. Since 1 m = 100 cm, a 1 m × 1 m square is 100 cm × 100 cm = 10,000 cm². Dividing an area by 100 is not enough.
Convert before multiplying
For dimensions in centimetres, divide each by 100 to obtain metres and then multiply. Or multiply in cm² and divide the result by 10,000. Choose one method and write the units at every step.
Keep realistic precision
Rounded dimensions can change an order. Record raw measurements for every section, especially around corners. Avoid many decimal places that imply more precision than your field measurements provide.