"We are calculating very hard. There is a lot of work going on. I expect (in) another four weeks, we should be able to wrap it up", Browne told reporters here amid intense flurry among the two remaining contenders Eurofighter and Dassault's Rafale.
"By mid-December we should have very good sense of who has been selected", he said after inaugurating the 51st conference of Indian Society of Aerospace Medicine (ISAM) at the Institute of Aerospace Medicine here.
Asked if he expects cost escalation vis-a-vis the contract, the Air Chief Marshal said, "I can't tell you anything till the time we finish that work".
The Defence Ministry had shortlisted France's Dassault Aviation SA's Rafale and EADS' Eurofighter Typhoon in April
Commercial bids from the two shortlisted vendors were opened on November four, marking the culmination of almost decade-long hunt for India's new mainline fighter.
On the process of selection, the Air Chief said there are a lot of complicated calculations and figures that needed to be checked and re-checked.