Casualty Statistics

There is no agreed definitive set of figures, but these are representative
COMBATANT CASUALTIES
Countries listed in order of total numbers mobilisedCP = Central Powers
CountryMobilizedKilledWounded
(not including shell shock)
Total casualtiesTotal casualties as % of mobilized
Russia12,000,0001,700,0004,950,0006,650,000
55%
Germany (CP)11,000,0001,718,0004,234,0005,952,000
54%
British Empire8,182,000908,000395,000 3,210,000
39%
made up as follows:
Great Britain 5,397,000 703,000 1,663,000 2,366,000
44%
India 1,500,000 43,000 65,000 108,000
7%
Canada 620,000 67,000 173,000 240,000
39%
Australia 330,000 59,000 152,000 211,000
64%
South Africa 149,000 7,000 12,000 19,000
13%
New Zealand 110,000 18,000 55,000 73,000
66%
Other British Africa 1 55,000 10,000 unknown unknown
18%+
British Caribbean 221,0001,0003,0004,000
21%
French Empire 7,500,000 1,385,000 4,266,000 5,651,000
75%
Austria-Hungary (CP) 6,500,000 1,200,000 3,620,000 4,820,000
74%
Italy5,500,000 462,000 947,000 1,409,000
26%
USA 4,272,500 117,000 204,000 321,000
8%
Turkey (CP) 1,600,000 336,000 400,000 736,000
46%
Japan 800,000 250 1,000 1,250
0.2%
Romania 750,000 200,000 120,000 320,000
43%
Serbia 707,000 128,000 133,000 261,000
37%
Bulgaria (CP) 400,000 101,000 153,000 254,000
64%
Greece 230,000 5,000 21,000 26,000
11%
Belgium 207,000 13,000 44,000 57,000
28%
Portugal 100,000 7,000 15,000 22,000
22%
Montenegro 50,000 3,000 10,000 13,000
26%

TOTAL59,798,5008,283,25019,513,00027,796,250
46%

Totals made up as follows:
Central Powers19,500,0003,355,0008,407,00011,762,000
60%
The Central Powers were Germany, Austria-Hungary, Turkey, Bulgaria
Opponents of Central Powers40,298,5004,928,250 11,106,00017,539,250
44%

CIVILIAN CASUALTIES
6.6 million, of which 2 million in Russia, and 2.1 million Armenians killed by the Turks
Millions of bereaved families and individuals, unknown thousands of shell-shocked veterans.

Based on a web page authored by Robert Wilde.
Most statistics from The Longman Companion to the First World War (Colin Nicholson, Longman 2001, pg. 248)

NOTES

1. The figure of 55,000 refers to soldiers who saw combat; the number of Africans involved as auxiliaries or otherwise is likely to include several hundred thousand. Troops were drawn from Nigeria, Gambia, Rhodesia/Zimbabwe, Sierra Leone, Uganda, Nyasaland/Malawi, Kenya and the Gold Coast. Figures for South Africa are given separately.

2. The British West Indies regiment drew men from across the Caribbean, including Barbados, Bahamas, Honduras, Grenada, Guyana, Leeward Islands, St. Lucia, St. Vincent and Trinidad and Tobago; the bulk came from Jamaica.

See Wikipedia for another set of data