Career
He was first in the national tournaments in 1918, 1920, 1921 (jointly), and 1926. Berndtsson played for Sweden in three Chess Olympiads:
In the 3rd Olympiad at Hamburg 1930 (+7−7=2);
In the 4th Olympiad at Prague 1931 (+5−5=8);
In the 5th Olympiad at Folkestone 1933 (+6−3=5).