The men's 400 metre freestyle event at the 1948 Olympic Games took place between July 31 and August 4 at the Empire Pool. This swimming event used freestyle swimming, which means that the method of the stroke is not regulated (unlike backstroke, breaststroke, and butterfly events). Nearly all swimmers use the front crawl or a variant of that stroke. Because an Olympic-size swimming pool is 50 metres long, this race consisted of eight lengths of the pool.
Swimming at the 1948 Summer Olympics – Men's 400 metre freestyle Wikipedia
Key: OR = Olympic record, Q = qualification by place in heat, q = qualification by overall place
Key: Q = qualification by place in heat, q = qualification by overall place
Key: OR = Olympic record