The Treaty of Bucharest (; ; ; ) was concluded on 10 August 1913, by the delegates of Bulgaria, Romania, Serbia, Montenegro and Greece. These territories would today include Novi Pazar in Serbia, Kosovo, and Ohrid, Štip, Kočani and Bitola in present-day North Macedonia. By this arrangement, Serbia increased its territory from and its population by more than 1.5 million.
Greece
The boundary line separating Greece from Bulgaria was drawn from the crest of Belasica to the mouth of the Mesta (Nestos), on the Aegean Sea. This important territorial concession, which Bulgaria resolutely contested, in compliance with the instructions embraced in the notes which the Russian Empire and Austria-Hungary presented to the conference, increased the area of Greece from and its population from 2,660,000 to 4,363,000.
The territory thus gained included large parts of Epirus and Macedonia, including Thessaloniki. The Greek-Bulgarian border was moved eastwards to beyond Kavala, thus restricting the Aegean seaboard of Bulgaria to an inconsiderable extent of 110 km, with only Dedeagach (modern Alexandroupoli) as a seaport. Within this region was also Florina. In addition, Crete was definitively assigned to Greece and was formally taken over on 14 December that year.
Bulgaria
thumb|right|180px|[[Punch (magazine)|Punch cartoon on the treaty: King Carol I of Romania holds King Peter I of Serbia and King Constantine I of Greece at gunpoint while he steals Southern Dobruja from Tsar Ferdinand I of Bulgaria.]]
Bulgaria's share of the spoils, although greatly reduced, was not entirely negligible. Its net gains in territory, which embraced a portion of Macedonia, Pirin Macedonia (or Bulgarian Macedonia), including the town of Strumica, Western Thrace, and 110 km of the Aegean littoral, were about , and its population was increased by 129,490.
Romania
thumb|Territory of Bulgaria ceded to Romania after the Bucharest Treaty
Bulgaria ceded to Romania Southern Dobruja, lying north of a line extending from the Danube just above Tutrakan (Turtucaia) to the western shore of the Black Sea, south of Ekrene (Ecrene); Southern Dobruja has an approximate area of , a population of 286,000, and includes the fortress of Silistra and the cities of Tutrakan on the Danube and Balchik (Balcic) on the Black Sea.
Perception
According to Anderson and Hershey, the severe terms imposed on Bulgaria contrasted the ambitions of its government upon the entry into the Balkan War: the territory eventually gained was relatively circumscribed; Bulgaria had failed to gain Macedonia, which was Sofia's avowed purpose in entering the war, and especially the districts of Ohrid and Bitola, which had been a main demand. With only a small outlet to the Aegean around the minor port of Dedeagach, the country had to abandon its project of Balkan hegemony. Romania also raised the question of the Balkan Vlachs (that is, the Aromanians and Megleno-Romanians), whom it considered its compatriots. Too distant to be annexed, however, Romania took Southern Dobruja as compensation. Romania was the strongest nation in the Balkans, and thus it believed that it had to acquire territory, given that its neighbors were being aggrandized. Romania's argument that it had turned the scales of the war was accepted without serious objections, due in part to Bulgaria's attitude not attracting much compassion. Despite not annexing the areas inhabited by Balkan Vlachs, Romania nevertheless obtained protection of the schools and churches of the Vlachs in the other Balkan states. Thus, Romania was the only Balkan country to obtain guarantees from all three of its neighbors, which pledged to recognize its interest in, and respect the autonomy of the Balkan Vlachs.
The status of the Vlachs in Bulgarian territories was settled on 4 August, in Greek territories on 5 August and in Serbian territories between 5 and 7 August. The 1913 Treaty of Bucharest itself was signed on 10 August. One notable aspect of this treaty was the lack of any real involvement from the European Great Powers. The Balkan states hurried to settle their differences before the Great Powers could again intervene in their affairs.
Subsequently, in 1914, Romania managed to impose its candidate for the throne of the Principality of Albania and support his reign by deploying military forces up to a battalion in strength. Romania's brief stint as a significant power thus started with the 1913 Treaty of Bucharest, but ended in October 1916. Having joined the First World War on the side of the Allies on 27 August 1916, Romania launched an invasion of Transylvania. However, by 16 October, Transylvania had been cleared of Romanian troops. One week later, on 23 October, Romania's chief seaport was captured by the Central Powers.