Short answers, pulled from the story.
The total number of military and civilian deaths in World War I is estimated at 15 to 22 million. An additional 21 million military personnel were wounded. At least two million military deaths were from disease, and six million went missing and were presumed dead.
Between nine and 11 million military personnel died in World War I. The Triple Entente (the Allies) lost about six million military personnel, while the Central Powers lost about four million. About two-thirds of those military deaths resulted from direct combat, with disease including the 1918 flu pandemic accounting for roughly one third.
Civilian deaths in World War I are estimated at six to 13 million. Micheal Clodfelter, who studies war losses, describes this figure as "hazardous to estimate" and cites a generally accepted figure of 6.5 million noncombatant deaths. The Ottoman civilian toll alone ranged from 2,000,000 to over 3 million, including victims of the Armenian Genocide.
About 140,000 Chinese workers recruited through the Beiyang government served on the Western Front with British and French forces during and after the war. The Commonwealth War Graves Commission records nearly 2,000 confirmed deaths from the Chinese Labour Corps, many from the 1918 influenza pandemic, though some Chinese scholars estimate the toll as high as 20,000.
The total number of Armenian deaths during World War I is generally held to have been 1.5 million. A Russian historian's 2004 handbook estimated 2.2 million total deaths among Armenian, Assyrian, and Greek victims of genocides committed by the Ottoman state during the war years.
The methodology each nation used to record and classify casualties was not uniform, and official sources themselves warn the figures cannot be considered comparable across countries. Some nations counted only combat deaths; others included disease, prisoner of war deaths, and laborers. The Commonwealth War Graves Commission later revised British and Allied statistics by adding deaths of colonial laborers from Africa, the Middle East, and China who had been omitted from the original 1921 rolls.