Born in Újpest,[1] he graduated from the Budapest University of Technology and Economics.
[5] After his retirement from professional sport, Krasznai took a coaching position by Újpesti Dózsa.
He trained among others Sándor Boros, Viktória Fekete and Zsuzsa Malovecz, all of whom became Hungarian champions in javelin throw.
[6] From 1957 Krasznai worked for electronics manufacturer Tungsram, first as design engineer and later as main constructor.
In 1990 he contributed to the development of a Miklós Németh designed javelin, the Flying Fantasy.