The national service, which comes into effect on April 1, was always expected to lose up to 3000 people from its payroll.
Its watchdog, the Scottish Police Authority (SPA), has devised a financial model for the cost of shedding 1400, a figure it called a "sensible mid-point between the best and already publicised worst-case scenarios."
The SPA, which will formally employ all staff, estimates it will have have to pay out £61.3m, most of which will come from the Scottish Government.
Annual savings of just less than £40m mean compensation for redundancy and early retirements should be covered within a year-and-a-half.
Exact figures, however, will depend how many people volunteer to leave.
The trade union Unison, which represents many civilian staff, believes they are bearing the brunt of the savings from a single force because of the SNP's commitment to maintain police numbers.
Spokesman Gerry Crawley said: "In our view, there is no necessity for this level of redundancy.
"It will result in police officers covering support staff roles, a situation that is not best value and which will end up costing the taxpayer more.
"There needs to be a balanced workforce and the arbitrary target on maintaining police officer numbers needs to be closely examined by the new service and the Scottish Government."
Labour supported plans for a single force before the SNP, but now believes the savings demanded of the service by the Government are "excessive".
Labour's Lewis Macdonald MSP said: "These plans must now mean police officers will be sitting in offices, staffing cell blocks or answering phones rather than be out on the streets."