Factbox: What does Lockheed's F-35 fighter jet really cost?

Lockheed Martin Corp is developing and building the F-35 Joint Strike Fighter, the Pentagon's most expensive weapons program, for three U.S. military branches and eight international partners.

The Pentagon released new cost projections for 78 major weapons programs on Thursday, including the F-35 program which showed the first decline in cost after years of increases and restructurings.

The partners who are helping fund the F-35's development include Britain, Australia, Canada, Turkey, Italy, Norway, Denmark and the Netherlands.

Israel and Japan have also placed orders and Singapore may soon follow suit, according to U.S. government sources. Lockheed is also bidding for a 60-fighter order from South Korea.

Following are some key figures about the F-35 program:

COST OF THE OVERALL PROGRAM

* Senior Pentagon officials have said they consider that price tag unaffordable. Program officials are taking steps to reduce the projected operating cost, including hiring engine maker Pratt & Whitney, a unit of United Technologies Corp , to cut the fuel burn of the engine by 5 percent.

COST PER JET

Over time, as production quantities increase, the jets are expected to start dropping in price. The per-plane forecasts factor in foreign orders, which are not included in the U.S. development, procurement and operating cost.

Bogdan recently said he expected to reach the target price at least for the A-model by 2020, when Australia is due to start buying the first of the 100 F-35s currently in its plans.

Lockheed executives say they believe the government's estimates are too conservative, and predict that the price of the new warplane will be even lower once the company starts full-rate production later this decade.

Critics of the program say Pentagon cost projections are probably too low, noting that further technical issues may well arise during flight testing of the new fighter jet.

The jet is built by Lockheed at its Fort Worth, Texas, plant, with Northrop Grumman Corp and BAE Systems Plc serving as key suppliers. Engines are built by Pratt & Whitney.

(Reporting by Andrea Shalal-Esa; Editing by Bob Burgdorfer)