Ireland's population is now at its highest level since the Famine, rising 7.6% since 2016 to 5.1m last April and with every county seeing population increases, particularly in Leinster.
It means the Dáil will have to add 11 or more TDs to keep up with the population increase.
Preliminary data from Census 2022, conducted in early April, shows there were 5,123,536 people in the country on census night, the highest level since 1841. That figure comprised 2,593,600 females and 2,529,936 males recorded, an increase of 7.7% and 7.5% respectively.
The rise in the population was attributed to a natural increase of 171,338 and estimated net inward migration of 190,333.
The areas of highest population growth were in Leinster. Longford's population grew by more than 14%, with Meath's population rising by 12.9% and the number of people living in Kildare and Fingal also rose significantly. Ten of the 12 counties showed a higher percentage increase than the national average.
In Munster, Waterford (+9.4%) had a higher percentage increase than that of the State overall. Other counties to see significant population growth since 2016 included Leitrim, up 9.5%, and Roscommon, up 8.4%, while population growth was below the national rate in counties such as Donegal, Monaghan and Cavan.
The preliminary data, published on Thursday by the Central Statistics Office, also shows that housing stock increased by 6% since 2016 to 2.1m, while the number of vacant dwellings, excluding holiday homes, fell by 9% to 166,752.
Cormac Halpin, senior statistician in the Census Division, said: "The preliminary results show that the total housing stock on 3 April 2022 was 2,124,590, an increase of 6.0% on the 2016 figure. There were 16,560 fewer vacant dwellings (-9.0%) in 2022 compared to 2016. This does not include holiday homes, of which there were 66,135, compared with 62,148 in 2016."
However, he said the definition of a vacant property did not mean it was available for immediate re-use. The CSO said a dwelling is classed as vacant by census enumerators if it is unoccupied for a short or long period around census night. For example, it may be unoccupied because it is up for sale or rent, under renovation, or if the owner has passed away, or is in a nursing home.
Preparations are already underway for the next census in 2027 and Mr Halpin said: "The publication of these preliminary results, less than 12 weeks after census night, is only possible thanks to the commitment and dedication of both our census field staff and the permanent census staff in Swords, as well as the continued support for the census from the public."
The next Dáil will have at least 11 more TDs than the current one based on the preliminary census data released today.
Under Article 16.2.2 of the Constitution, there should be one TD for every 30,000 people, but today's data from the Central Statistics Office (CSO), shows that 38 of 39 constituencies are above that figure, with there now being one TD for every 32,022 people.
Adding TDs will mean redrawing constituency boundaries, a move to be undertaken by the Electoral Commission when it is established. The Commission will be established under the Electoral Reform Bill which is due to pass the Seanad next week.
New constituencies could be formed and seats added to existing areas, all of which will have an impact on the shape of the next Dáil. However, 171 TDs would be two more than can currently be accommodated in the Dáil chamber. There are currently 169 seats available.