Carpenter was born in Moretown, Vermont in the Mad River Valley of the Green Mountain range. His pioneering forebears were English, and came to America soon after the Pilgrims. His grandfather Cephas Carpenter (1770–1860) helped establish Moretown, owned a store, served as a colonel in the militia and took part in the War of 1812. Cephas Carpenter served in local office including justice of the peace, and though not a member of the bar, possessed wisdom and eloquence that led to a career as an advocate in the local courts.