It has also been written that up…

It has also been written that up to ninety percent of the male population may have been killed, though this figure is without support.

According to one numerical estimate, the prewar population was approximately five hundred and twenty-five thousand Paraguayans (a survey of fourteen estimates varied between three hundred thousand and one million three hundred and thirty-seven thousand (F. Chartrain: "L'Eglise et les partis dans la vie politique du Paraguay depuis l'Indépendance", Paris I University "Doctorat d'Etat", 1972, pages 134–135. Chartrain’s own calculation, based on a 1879 census and in the military forces, gives between seven hundred thousand and eight hundred thousand inhabitants).

A census in 1871 gives 221,079 inhabitants, of which 106,254 are female, 86,079 are children with no indication of sex or upper age limit, and 28,746 are male.

These figures, considering the local situation, cannot be more than a very rough estimate; many men and boys had fled during the war to the countryside and forests.

As such, accurate casualty numbers may never be determined.

A 1999 study by Dr. Thomas Whigham from the University of Georgia published in the Latin American Research Review under the title "The Paraguayan Rosetta Stone: New Evidence on the Demographics of the Paraguayan War, 1864–1870" and later expanded in the 2002 essay titled "Refining the Numbers: A Response to Reber and Kleinpenning" gives somewhat more accurate figures.

Based on a census carried out after the war ended, in 1870 and 1871, Dr. Whigham had come up with a much lower figure of one hundred and fifty thousand to one hundrde and sixty thousand Paraguayan people left, of which only twenty-eight thousand were adult males.

This leaves a woman/man ratio of four to one, while in the most devastated areas of the nation the ratio was as high as twenty to one.

Regarding the population before the war, Dr. Whigham used a census carried out in 1846 in order to calculate, based on a population growth rate of 1.7% to 2.5% annually (which was the standard rate at that time and again the aforementioned omissions), that the immediate pre-war population in 1864 was approximately fouyr hundred and twenty thousand to four hundred and fifty thousand Paraguayans.

This figure produces a loss of 60% to 70% of the population.

Of the approximately one hundred and twenty-three thousand Brazilians who fought in the Paraguayan War, the best estimates are that around fifty thousand men died.

Uruguayan forces counted barely fifty-six hundred men, of whom about thirty-one hundred died.

Argentina lost around eighteen thousand of its thirty thousand combatants.