The measurement of an existing property can NOT be 100% accurate. If someone told you they have 100% accuracy, DO NOT TRUST THEM.
There will be more or less 2~5% discrepancy in floor plan measurement due to multiple reasons. Less than 5% discrepancy in real estate property surveying work is acceptable and we will also put an explanatory note on the floor plan file: “DIMENSIONS, AREAS, LAYOUTS AND DETAILS ARE APPROXIMATE AND SHOULD BE CONSIDERED ILLUSTRATIVE ONLY”.
For Commercial Property, the area measurement and calculation are based on BOMA standard.