To enhance the degree of precision such that, in lifting of the restrictions on a measuring range of planimeters measuring the area of figures and measuring of the measurement of area with high precision by correcting shortcut error due to a caster of handy planimeter, area is metered by loading calculation software of relation between two sides and the contained angle and relation between three sides or two sides and the contained angle and area of triangles on Kirbymeters and handy planimeters and by loading correction calculation software using trigonometric function on handy planimeters.

Functionality calculating area is given to Kirbymeters and handy planimeters on which a calculation software on relation between two sides and the contained angle and relation between three sides or two sides and the contained angle and area of triangles are loaded. A shortcut correcting software is loaded on a handy planimeters to aim at enhancement in precision.