On earth, the meridian has an approximate length of 20,003.93m. 20,003.93km / 180 / 60 ≈ 1,852.22m ≈ 1,852m = 1NM Note, however, that 20,003.93km / 2

On earth, the meridian has an approximate length of 20,003.93m. 20,003.93km / 180 / 60 ≈ 1,852.22m ≈ 1,852m = 1NM Note, however, that 20,003.93km / 200 / 100 ≈ 1,000.20m ≈ 1,000m = 1km so if we used gradians/gon where the full turn corresponds to 400 instead of 360, the kilometer would be an approximation as good as the (international) nautical mile.