The refugee influx will cost Germany up to 55 billion euros (60 billion dollars) a year, the Kiel Institute for the World Economy (IfW) estimated on Friday.
A simulation carried out by the IfW - one of Germany's foremost economic research centres - predicted the annual figure would vary between 25 and 55 billion euros.
The author of the study, Matthias Luecke, acknowledged a high level of uncertainty in the figures, particularly with regard to the number of refugees in the country and the speed with which they are integrated into Germany's jobs market.
Even with figures at the high end, costs would remain below 2 per cent of gross domestic product and thus manageable, he said.
The IfW researchers predicted that as little as 360,000 refugees could arrive in Germany each year from 2018, down from a million this year. The costs would then sink to 25 billion euros annually. At a million refugees, the figure would be up to 55 billion.
The study assumes that 30 per cent of the refugees will return to their country of origin and that 20 per cent would have difficulty finding jobs.
Contradicting other predictions, the IfW researchers said the influx of refugees would not have a positive effect on general prosperity. While demand and economic output might rise, social expenditure would also increase, they said.
Other researchers have seen the migrants, many of them young men, as boosting economic output in a rapidly ageing society.
The civil war in Syria has been a major factor in the huge rise of asylum seekers travelling to Germany.