*rubs eyes* An Electoral Commission! https://twitter.com/depthousingirl/status/1347481082426490880

The next census (April 2022) is likely to show the population at just over 5 million, so the likelihood is that the next Dáil will have 172 TDs, 12 more than now
The Constitution requires there to be an average of one TD for every 20,000-30,000 people. The next census will show a population of ballpark 5.015 million, so 168 is the bare bare minimum but would still leave some constituencies spread quite thinly. Higher end more likely