The casualties of the Napoleonic Wars (1803–1815), direct and indirect, are broken down below:

Note that the following deaths listed include both killed in action as well as deaths from other causes: diseases such as those from wounds; of starvation; exposure; drowning; friendly fire; and atrocities. Medical treatments were changed drastically at this time. 'Napoleon's Surgeon', Baron Dominique Jean Larrey, used horse-drawn carts as ambulances to quickly remove the wounded from the field of battle. This method became so successful that he was subsequently asked to organize the medical care for the 14 armies of the French Republic. With the partial exception of the United Kingdom, all of the states at the time did not keep especially accurate records, so calculating losses is to a certain extent a matter of conjecture.

The first definitive estimate of French war dead occurred in 1832, when the head of the conscription division under the imperial regime filed a report to the Chambre des Pairs on the drafting of a new law on recruitment. This report estimated that 1.7 million French soldiers died in the 1803-1815 wars. The above figures are per Gaston Bodart, who found the latter figure to be an overestimate (and likely including deaths in 1792-1799) after closer analysis of the data. Bodart (1916) and Meynier (1930) both calculated between 800,0000 and 1,000,000 French soldiers (not counting allies) dead in the period of 1803-1815 (taking the ratio of French to allied losses and combat to noncombat losses, Bodart's estimates would put specifically French deaths at some 824,000). Boris Urlanis used Bodart's figure for 306,000 French soldiers killed in combat but assumed a higher noncombat death ratio of about 3:1, putting total French military deaths at 1,200,000.

Jacques Houdaille later performed a more detailed study using the army's nominal rolls, taking a statistical sample of them at a scale of 1:500 (3 million French soldiers fought in the 1792-1815 wars, about 2.8 million on land and 150,000 at sea; 2.3 million were mobilized in 1800-1815). According to his research, some 439,000 soldiers and officers from France were confirmed dead in combat or in hospital and 706,000 were declared missing. Houdaille then estimated, using a survey of civil registers, how many former soldiers returned home after 1815 without being registered by the military administration. Deducting these men, he concluded that some 900,000 to 1 million French soldiers died from 1800 to 1815, consistent with Bodart, Meynier, and Ulranis's shared range of 800,000 to 1,200,000 French dead for 1803-1815, and implying a roughly 2:1 rate of noncombat to combat deaths. Deaths were slanted heavily towards the later years of the conflict and roughly half of them happened in 1812-1814.

Naval, coastal, and colonial actions in 1803-1815 accounted for a total of 13,750 French and allied battle deaths, and therefore from 37,000 to 55,000 total military deaths (Bodart's total of 371,000 French and allied killed out of 1,000,000 dead indicates a noncombat to combat death ratio of about 1.7:1 compared to Ulranis's 3:1 and Houdaille's 2:1). Inclusive of these, Bodart breaks down French and allied killed in action figures by year as follows:

Casualties taken in specific campaigns include:

Peninsular War (1807-1814):

Invasion of Russia (1812):