Around 900,000 UK citizens are living in other European Union countries, according to new analysis by official statisticians.
The estimate is lower than the 1.2 million figure that has been widely used in discussions about expats living on the continent following the Brexit vote.
Demographers said the latest number is based on citizenship, whereas other tallies focused on country of birth.
The Office for National Statistics (ONS) used census figures from 2010 and 2011 to examine the number of UK citizens who have lived for at least a year in other EU member states.
Its analysis put the total size of the group at 890,299, with the report also showing that:
:: The largest age group is 30 to 49 years, accounting for 280,000 people;
:: Spain is host to the largest number of British citizens living in the EU, at 308,805, followed by France (157,062), Ireland (112,090) and Germany (96,200);
:: Just over a third (101,045) of British citizens living in Spain are aged 65 and over, and this is also the largest age group in Malta (2,157);
:: Most British citizens living in Cyprus, Portugal, Greece, France and Bulgaria are aged 50 or over;
:: The highest concentration of British citizens is in Cyprus, with 2.9% of the population holding only British citizenship;
:: British citizens make up 0.2% of the population of the EU (excluding the UK) and European Free Trade Association (EFTA) states - Iceland, Liechtenstein, Norway and Switzerland - combined.
Jay Lindop, ONS deputy director for population, said the analysis was produced "to give a clearer picture" of UK citizens living in the EU and European Economic Area.
She added: "These data are from censuses held in 2011, the most recently available source of comparable data for all countries.
"Our research suggests that there has not been a great deal of change in the numbers between 2011 and 2016.
"The overall figure of 900,000 is different to estimates which have been cited previously in public debate, which focus on country of birth rather than citizenship."
Separate data which have been widely quoted as giving an estimate of 1.22 million UK-born migrants in other EU member states apply the country of birth definition for 25 out of 27 nations, according to the report.
It said these figures will include many Irish and Polish citizens while not counting British citizens born overseas.
The status of expats in Europe has fallen under the spotlight in the wake of the referendum vote.
Ministers have said they want to protect the status of EU nationals already living in Britain, and that the only circumstances in which that would not be possible is if a reciprocal approach is not adopted for British citizens in European member states.