Some of Häyhä’s figures are from a Finnish Army document, counted from the beginning of the war, 30 November 1939:
22 December 1939: 138 sniper kills in 22 days[21]
26 January 1940: 199 sniper kills (61 in 35 days)[22]
17 February 1940: 219 sniper kills (20 in 22 days)[7]
7 March 1940 (one day after he was wounded): total of 259 sniper kills (40 in 18 days)[7]
Häyhä never discussed it publicly, but his own private memoir, discovered in 2017, states a number. He begins by stating that “this is his sin list”, and estimates the total number he shot to be around 500.
Jesus!
From his Wiki page