According to some sources, such as Robert Brantberg, a writer specializing in military history, Häyhä shot as many as 542 Red Army soldiers with his rifle.[11] Antti Rantamaa also credited Häyhä with 542 kills in his book.[2] According to the article published by the historian, docent Risto Marjomaa, published by Kansallisbiografia, the correct number of casualties could be around 200 soldiers[3], which also makes him one of the most effective snipers of all time.[12] The number of enemies killed by Häyhä did not include those shot with a machine gun as a group leader, which according to some sources was more than 200.[13]

The official number of Soviet soldiers killed by Hähä as a sniper with a rifle was based on the observations of a specially appointed observer or fellow combatants.[11] Counts were not made when several shooters were shooting at the same target. Häyhä made all his kills in just three months before he was wounded. According to Brandtberg, among other things, Häyhä shot a record 25 Soviet soldiers in one day, December 21, 1939, which he could only announce when he returned to the "dug" by mentioning the number "twenty-five".[13][6] The total balance of the three days of Christmas was 51 men.[11] Of course, the result of the hit could not be confirmed, as the targets were on the Russian side.[3] The matter is further complicated by the fact that Häyhä's achievements were used as a propaganda tool: the press built a hero myth around Häyhä early on.[12]

Even before Christmas 1939, according to Häyhä, the writer Mika Waltari had visited to photograph him and Juutiais "like some miracles".[14]