izračunati

1. to calculate; to work out
   Izračunaj koliko ukupno treba da platimo. — Work out how much we have to pay in total.
   Izračunala sam da nam treba još dve hiljade dinara. — I calculated that we need another two thousand dinars.
2. to estimate; to reckon
   Izračunao je da ćemo stići pre mraka. — He reckoned we would arrive before dark.

The imperfective counterpart is izračunavati or računati.