Muslim immigrants have been a politically sensitive topic in Europe following the influx of newcomers between 2014 and 2016. The estimates draw on Pew's own analysis as well as census data and other sources.
Europe's Muslims have more children than members of other religious groups, or people of no religion, the study showed.
Cyprus was found to have the highest share of Muslims in the European Union (25.4 percent), due largely to the Turkish Cypriot community in the north of the island.
The report found that Germany was the top destination for Muslim refugees between 2010 and 2016, whereas the United Kingdom took in the highest number of regular Muslim migrants.
However, in Germany's case, the country's increase in Muslims mostly come from refugees as opposed to regular migration. Europe's non-Muslim population is estimated to decline.
All three used a mid-2016 estimate of 25.8 million as a baseline, but assumed different future migration rates.
A revealing survey by Pew Research Center, "Europe's Growing Muslim Population", looks at the future of the 25.8 million Muslims now residing in European countries.
A "high" migration scenario imagines that record refugee flows into Europe between 2014-16 continue into the future with the same religious composition, along with regular migrant arrivals.
PARIS: Muslims could make up over 11 percent of Europe's population in the coming decades, compared with just under 5 percent now, if legal migration levels are maintained, a report by a US-based think tank said on Thursday.
Each scenario predicts that Europe's non-Muslim population will decline significantly - from 521 million to an estimated 482 million.
Europe's non-Muslims, the report says, are expected to decline in total number in each scenario.
"The zero migration and the high-migration scenario are really thought experiments, kind of what it could be like at either end of the spectrum", said Conrad Hackett, one of the lead researchers of the study.
The impact of the scenarios is uneven across different European countries, depending on government policies and the varying numbers of Muslim refugees arriving to date.
Another factor that may affect the number of Muslims in Europe is whether rejected asylum-seekers return to their country of origin voluntarily or through forced deportation. In Sweden, almost a third of the population (4.5 million, or 30 percent) would be Muslims, whereas in Austria and Germany Muslims would represent up to 19 percent of the population.
Sweden's Muslims, who were at 8 per cent in 2016, would account for 31 per cent of the population in that same scenario.
In this "high scenario", Germany would be home to 17.5 million Muslims by 2050, by far the highest number of Muslims in Europe.
This is partly down to a record number of people seeking asylum in Europe as they flee conflicts in Syria and other predominantly Muslim countries, but mainly due to normal migration from Muslim countries.
Migrants arriving in Munich, September 2015.
The Muslim share of Germany's population could grow from 6.1 per cent in 2016 to 19.7 per cent in 2050 if high migration continues, whereas over the border Poland's share would change from 0.1 per cent to 0.2 per cent in the same scenario. The European average fertility rate is 2.6 for Muslims compared to 1.6 for non-Muslims. Euronews' Insiders programme recently spoke to one young activist in Hungary who claimed statistics showed that "in 50 or 60 years' time, our continent's population could be replaced, from an ethnic point of view... white people will disappear".