Kaarlo Oskari Hämäläinen has officiated 169 matches on record, averaging 3.8 cards and 14.5 fouls per game — a balanced official. A player is dismissed roughly once every 4 games, and the spot is pointed to 0.37 times per match. Home teams win 44% of matches under him, drawing 25% and losing 31%. Most active in the Veikkausliiga (115 matches). 35% of his bookings come after the 75th minute, with the first card around the 33'. He cards more than 67% of Veikkausliiga 2024 referees.