That's according to the latest Census figures.
The latest Census figures show that there were over 5.1 million people in the State on Census night, which took place in April last year.
That is an 8% (387,274 people) increase on April 2016 figures.
County Kildare's population increased by 11%, while the county continued to be one of the counties with the youngest age on average, at 36.9.
Nationally, the population includes more females than males.
There are 2.6 million females living in the country compared to 2.5 million males.

Kfm Obituary Announcements
Thousands Step Out at Dawn in Support of Mental Health
"Like A Bull In A China Shop": Kildare TD Criticises Media Minister Amid Proposed Social Media Ban For Under 16s
Darkness Into Light Events Taking Place Across Kildare
Gardaí Recover Pellet Gun After Alleged Assault In Sallins
Man Due Before Court Following Seizure Of Firearms And Ammunition In Maynooth Yesterday
Parents And Guardians Urged To Complete Applications For School Transport, As Deadline Looms