Omote-daka was calculated based on the land survey officially recognized by the Edo bakufu; however, in many domains the actual uchi-daka was higher than omote-daka and also increasing, thanks to the progress of development of new field in 17th century, the land survey within domains that was based on the increased productivity by innovation of agricultural technique (farming equipments, fertilizer), and tax reform by monopolization of indigenous products.
表高は江戸幕府公認の検地によって算定された石高だが、実際の藩内では17世紀に進んだ新田開発や、農業技術（農機具・肥料等）の革新による生産力の増大に基づいた藩内検地、専売制による特産品の税高改定などによって、多くの藩では内高は表高を上回って増大していた。