The map projection that is best for calculating directions is the: polar mercator interrupted-area globe

The Mercator map projection is considered to be the best for calculating directions.

Explanation:

Though the Mercator map projection is known for causing longitudinal and latitudinal distortion to a great extent, it is still relied upon so much because the distortions caused in this projection are always two-way, i.e., a distortion in the latitude also brings a distortion in the longitude to balance and equate the distortions.

Owing to this quality of the Mercator map projection, the calculation of directions using this projection gives the best and precise results.