Princeton is strategically situated just south of the picturesque Princeton Ridge, which defines much of its geographical landscape. The town lies in a low-lying area, which has resulted in occasional challenges with cell phone signal reception for residents. According to data from the U.S. Census Bureau, Princeton encompasses a total area of 18.41 square miles (47.69 km²), with 17.95 square miles (46.48 km²) designated as land and 0.47 square miles (1.21 km²) as water, accounting for approximately 2.53% of the total area.

Over the years, several unincorporated communities, including Cedar Grove, Port Mercer, Princeton Basin, and Jugtown, have been absorbed into the Greater Princeton area. Despite their incorporation, these communities continue to maintain their distinct identities, contributing to the rich tapestry of Princeton’s cultural landscape.

Geographically, Princeton shares borders with several municipalities, including Hopewell Township, Lawrence Township, and West Windsor Township in Mercer County, as well as Plainsboro Township and South Brunswick Township in Middlesex County. Additionally, it adjoins Franklin Township and Montgomery Township in Somerset County, making it a central hub within this interconnected region.

Princeton is served by multiple United States Postal ZIP codes, including 08540, 08541 (designated for the Educational Testing Service), 08542 (primarily covering the old Borough), 08543 (PO boxes), and 08544 (for the University). This diverse geographic makeup, combined with its rich history and vibrant communities, positions Princeton as a notable area in New Jersey, attracting residents and visitors alike.