Inkom sits in a narrow bend of Marsh Valley. Grass-covered hills surround the valley, rising gradually to the lofty peaks of Scout Mountain to the southwest and the Portneuf Mountains to the southeast. Ancient lava flows protrude from the bottoms of the hills and a large mesa of lava sits east of the town, ending in an abrupt black cliff. The Portneuf River flows past the west side of town.
The narrow valley is an important passage for travel through the surrounding mountains. Idaho's first railroad passed this way in the 1800s, and in the early 1900s U.S. Highways 91 and 30 took this route. Today a modern railway and Interstate 15 both squeeze past the town right next to the lava cliffs.
Inkom had a population of 738 as of the 2000 census. The elevation is 4547 feet.