The Projection System used in Nepal is the UTM (Universal Transverse Mercator). Mercator projection is Conformal Cylindrical Projection. In Transverse projection, Earth is wrapped around a cylinder in such a manner that point of tangency between Globe and Cylinder is a meridian, or line of longitude, called Central Meridian. In Conformal or Orthomorphic Projection, the shape/angle is preserved even though the length and breadth may distort.
UTM consists total of 60 zones of longitude each of 60 extending from 1800 W to 1800 E. 1800 W to 1740 W is designated as zone 1 with the central meridian of 1770 W and other zone goes as so on and so further manner. Further zone are divided in rows with a difference of 80. These zone extend from 800 S Latitude to 840 N latitude. The first Latitude zone is designated with letter C for 800 S to 720 S latitude.
Nepal lies in the UTM zone of 440N and 450N. The scale factor is 0.9996 for the central meridian. 10 49’ east or west of central meridian has the scale factor of 1.
In recent years because Nepal has greater East-West expansion so as to increase accuracy for cadastral survey and various other purpose,UTM has been modified to MUTM(Modified UTM); Gauss-Krueger projection-based coordinate system, thus the “modified” designation. In this projection system Earth is divided in 120 zones each of 30. Nepal has central meridian of 810,840 and 870. The scale factor of 0.9999 is used for central meridian normally for 840 and 00 55’ east or west of central meridian has the scale factor of 1 (meaning no distortion). False Easting at central meridian is 500 000 m in order to keep all the coordinates within the country positive, and False Northing at the Equator is 0 m.