The average accuracy has been tested to be 95-97%. LiDAR devices are usually more precise, always within 3%. Do note that we are constantly making changes to our algorithms to improve the accuracy and as hardware improves, we are certain this will improve.
We did some research and you have as much difference between a Cubicasa scan and a person measuring than between 2 persons measuring the same property.
Elements that can affect accuracy
Be aware that accuracy is affected by various different factors like scanning style, lightning conditions, and how many objects are preventing visibility to the floor/wall line. Please make sure you follow our recommended best Scanning Techniques.
Also as we mentioned it, LiDAR devices generally gives more accurate results.
Results different from public records
First thing first: public records don't give you more guarantee on accuracy as no standard is imposed. It could have been a experienced appraiser with a laser or someone new on the job doing manual measurements and roughly rounding things.
We have more details about it in our GLA FAQ which we encourage you to read if you're an appraiser.