The main characteristic of Bulgaria's topography is alternating bands of high and low terrain that extend east to west across the country. From north to south, those bands are the Danubian Plain, Stara Planina (the Balkan Mountains), the central Thracian Plain, and the Rhodope Mountains. The easternmost sections near the Black Sea are hilly, but they gradually gain height to the west until the westernmost part of the country is entirely high ground.

More than two-thirds of the country is plains, plateaus, or hilly land at an altitude less than 600 m. Plains (below 200 m) make up 31 % of the land, plateaus and hills (200 to 600 m) 41 %, low mountains (600 to 1,000 m) 10 %, medium-sized mountains (1,000 to 1,500 m) 10 %, and high mountains (over 1,500 m) 3 %. The average altitude in Bulgaria is 470 m.