Australia's new nuclear-powered submarine deal is estimated to cost $116 billion on top of sunk costs from the scrapped French deal, a defence think tank says.
The Australian Strategic Policy Institute weighed up the options available for the federal government for the eight-boat program and flagged that costs are likely to be higher due to Australia's choice in build strategy.
The analysis concluded it would be at least 20 years before a submarine would be in the water with the build likely ranking as Australia's largest and most complex endeavour.
Australia is due to consider its options over the next 18 months as defence officials decide whether the go with a United States or British design under the new trilateral AUKUS security alliance.
ASPI's report details the possible pathways forward and compared the potential for US and UK submarine build timelines.
It found the UK submarine program would likely be available to start by the end of the decade based on the country's current build schedule while any US boats could be pushed out until after 2030.
Australia will also need to weigh up whether to proceed with a continuous build, where the next boat is built in time to replace the nuclear powered submarine when it comes to the end of its life, or an economic build, where they would be produced in the most efficient manner possible.
Each include trade-offs between cost, scheduling and security.
The economic build would cost between $116 billion and $129 billion while the continuous build would set Australia back between $153 billion and $171 billion.
The costs account for inflation. ASPI notes pinpointing costs are unreliable due to the uncertainty but the broad estimate covers most key variables, including using eight submarines as a minimum, engaging local construction and boats weighing between 7000 and 10,000 tonnes based off current designs.
