The Amherst district lies between 14° 56´ and 17° 2´ North and 97° 27´ and 98° 51´ East, and forms a part of the Tenasserim Division of Lower Burma.

It is bounded by the Thatôn District on the north, Siamese Territory on the east, Tavoy District on the south and the Gulf of Martaban on the west, and contains an area of 7,105 square miles.

On the north, the Salween, Gyaing, Hlaingbwè and, Pata rivers form for the most part a natural boundary. On the east the Thaungyin River and the mountains, and on the west the Gulf of Martaban also provide well defined natural boundaries.

On the south the boundaries are mainly arbitrary and not so well defined.