Scottish taxpayers could pay about £1.5bn a year less for defending an independent Scotland than they currently pay towards UK defence spending, according to a report.
The Royal United Services Institute (RUSI) study claimed annual costs could be cut from £3.3bn to about £1.8bn.
The report outlined the idea of a "relatively modest" independent Scottish defence structure.
It would be comparable in strength and size with other small European states.
The report - co-written by economist Richard Marsh and Stuart Crawford, a former SNP defence advisor and British Army Lieutenant Colonel - examined what the armed services of an independent Scotland would be for.
It also outlined a model for how they might be organised and deployed.
It estimated Scottish defence expenditure was £3.3bn in 2010-2011, and that over the last five years about 2.2% of Scotland's economy on average had been spent on contributions to UK defence spending.
The authors suggested those figures could be "markedly lower" were Scotland to be independent.
The report assumed the creation of Scottish Defence Forces (SDF) with a separate navy, air force and army - with no place for nuclear weapons in an independent Scotland.
It envisaged that the SDF "would probably have a regional, rather than global, focus".
The paper outlined a Scottish Navy with a surface fleet of between 20 and 25 ships, including Type 23-class frigates but not submarines, claiming that would cost £650m a year to run.
A Scottish Air Force would include about 60 aircraft including BAE Hawk, C-130 Hercules, Chinook and Sea King helicopters but no Typhoons or Tornados. It estimated the cost of that service at £370m a year.
The report also suggested a Scottish Army could have 10,000-12,500 personnel, and include a brigade-sized force, three combat battalions plus supporting arms, allowing it to deploy and sustain itself in a combat zone. The report estimated those costs at £820m a year.
The paper acknowledged "potential issues" for an independent Scotland, such as the need for an arrangement with the rest of the UK to supply intelligence-gathering, cyber-warfare and cyber-defence expertise at GCHQ.
The authors also warned that the future cost of purchasing and maintaining equipment of its forces may be higher due to smaller orders, while recruitment and training of personnel "'may prove problematic" in the early years.
The report argued: "Should the government of an independent Scotland, of any political hue, have the political will to establish an SDF along the lines described herein, then it can certainly be done.
"An SDF would be necessary, feasible and affordable.
"Scotland can have its SDF if it chooses to do so, although the embryonic Scottish military establishment would no doubt have to fight its corner energetically for a proper share of government funding against all the other demands of national administration."