Saggart's population grew by almost half in five years according to the Central Statistics Office.
The state's number crunchers have been examining population migration figures from last year's census results.
The 46% growth spurt in Saggart makes it Ireland's fastest growing town. There are now 3,133 inhabitants.
The nearest town is Rathcoole which has experienced the next largest increase.
It went from 3,421 to 4,351 - that's a 27% increase since the previous census in 2011.
Swords is Dublin's largest town with just under 39,250 people.
Dublin has 1,347,359 inhabitants with only 2% of those living in rural parts of the county.
1.2 million people gave their county of birth as Dublin
Of those born in the capital but now living elsewhere, over half in the towns of Johnstown (56%) and Kill (53%) in Kildare, and Ratoath (55%) in Meath were Dublin-born.