The Spaulding Turnpike (New Hampshire Route 16) runs north to south through Milton, with access from Exit 17 (New Hampshire Route 75) in the south, near Milton village, and from Exit 18 (New Hampshire Route 125) in the north, just south of the Wakefield town line.
According to the United States Census Bureau, the town has a total area of , of which are land and are water, comprising 3.41% of the town.