There are many sources that list casualties figures from the Great War. One particularly good reference, with commentary and analysis, is: Michael Clodfelter, Warfare and Armed Conflicts: A Statistical Reference to Casualty and Other Figures, 1618-1991 (London: McFarland & Company, 1992. 2 vols.). Because of the enormity of the numbers involved, in many cases the figures for the separate countries are often only best guesses or rough approximations. A contemporay calculation was done for Current History by Walter Littlefield, "War Casualties of All Nations" (February 1919) resulting in a total of about 36 million casualties (*.pdf file).
| Country | Dead | Wounded | POW/MIA | Total | Mobilized |
| Austria-Hungary | 922,500 | 3,620,000 | - | 4,542,500 | 7,800,000 |
| Belgium | 13,715 | 44,686 | - | 58,401 | 267,000 |
| British Empire | 908,371 | 2,090,212 | 270,117 | 3,268,700 | 8,904,467 |
| Bulgaria | 131,344 | 152,390 | - | 283,734 | 1,200,000 |
| France | 1,365,735 | 4,266,000 | 477,800 | 6,109,535 | 8,410,000 |
| Germany | 1,808,546 | 4,247,143 | 772,522 | 6,828,211 | 11,000,000 |
| Greece | 5,000 | 21,000 | - | 26,000 | 230,000 |
| Italy | 462,391 | 953,886 | 524,000 | 1,940,277 | 5,615,000 |
| Japan (see note) |
300 | 907 | - | 1,207 | 800,000 |
| Montenegro | 3,000 | 10,000 | - | 13,000 | 50,000 |
| Portuguese Empire | 167,222 | 13,751 | 6,895 | 187,868 | - |
| Romania | 335,706 | 120,000 | - | 455,706 | 750,000 |
| Russia (official) | 643,214 | 2,754,202 | 3,638,271 | 7,036,087 | 12,000,000 |
| Russia (estimate) | 1,700,000 | 4,950,000 | - | 6,650,000 | 12,000,000 |
| Serbia | 125,000 | 133,148 | - | 258,148 | 707,343 |
| Turkey | 325,000 | 400,000 | - | 725,000 | 2,850,000 |
| US | 116,608 | 204,002 | - | 320,610 | 4,743,826 |
| TOTALS | 7,333,652 | 14,576,327 | 5,689,605 | 27,599,584 | 65,327,636 |
Another common set of figures is from the 1997 Information Please Almanac: Atlas & Yearbook (Boston: Houghton-Mifflin, 1997).
| Country | Dead | Wounded | POW/MIA | Total | Mobilized |
| Austria-Hungary | 1,200,000 | 3,620,000 | 2,200,000 | 7,020,000 | 7,800,000 |
| Belgium | 13,716 | 44,686 | 34,659 | 93,061 | 267,000 |
| British Empire | 908,371 | 2,090,212 | 191,652 | 3,190,235 | 8,904,467 |
| Bulgaria | 87,500 | 152,390 | 27,029 | 266,919 | 1,200,000 |
| France | 1,357,800 | 4,266,000 | 537,000 | 6,160,800 | 8,410,000 |
| Germany | 1,773,700 | 4,216,058 | 1,152,800 | 7,142,558 | 11,000,000 |
| Greece | 5,000 | 21,000 | 1,000 | 27,000 | 230,000 |
| Italy | 650,000 | 947,000 | 600,000 | 2,197,000 | 5,615,000 |
| Japan | 300 | 907 | 3 | 1,210 | 800,000 |
| Montenegro | 3,000 | 10,000 | 7,000 | 20,000 | 50,000 |
| Portugal | 7,222 | 13,751 | 12,318 | 33,291 | 100,000 |
| Romania | 335,706 | 120,000 | 80,000 | 535,706 | 750,000 |
| Russia | 1,700,000 | 4,950,000 | 2,500,000 | 9,150,000 | 12,000,000 |
| Serbia | 45,000 | 133,148 | 152,958 | 331,106 | 707,343 |
| Turkey | 325,000 | 400,000 | 250,000 | 975,000 | 2,850,000 |
| US | 116,516 | 204,002 | 0 | 320,518 | 4,734,991 |
| TOTALS | 8,528,831 | 21,189,154 | 7,746,419 | 37,464,404 | 65,418,801 |