How precise does an ANSI Z765 measurement have to be?
Published August 27, 2026
ANSI Z765 asks for measurements taken to the nearest inch or tenth of a foot and finished area reported to the nearest whole square foot (nearest 0.1 square meter in metric). The standard does not require a laser or any specific tool, only that precision.
Why two appraisers get different numbers
Even at inch precision, a 50-foot wall measured by two people will differ by an inch or so, and a house has a lot of walls. Differences of 1 to 2% between careful measurers are normal. A difference of 10% means somebody applied a rule differently (usually the above/below grade test or the ceiling height rule), not that somebody measured badly.
Rounding in practice
Round at the end, not wall by wall. Keep the dimensions as measured, calculate the area, then round the final finished-area figures for above grade and below grade separately.