Castlereagh Population 2026
Castlereagh has a population of 56,679, making it the #206 biggest city in 🇬🇧 United Kingdom, located in Northern Ireland. Roughly 0.1% of United Kingdom's population lives here. It is about 158× smaller than London, the country's biggest city.
Population (city proper)
56,679
Rank in United Kingdom
#206
Coordinates
54.57°N, 5.88°W
~29 m elevation · Europe/London
Distance to capital (London)
514 km
319 miles, straight line
Other big cities in Northern Ireland
| City | Population | Rank in United Kingdom |
|---|---|---|
| Belfast | 348,005 | #13 |
| Derry | 83,652 | #127 |
| Lisburn | 77,506 | #140 |
| Newtownabbey | 63,860 | #174 |
| Bangor | 61,011 | #189 |
| Craigavon | 59,236 | #196 |
| Portadown | 32,926 | #378 |
| Newtownards | 29,363 | #422 |
Cities near Castlereagh
- Belfast348,005 people · ~4 km away
- Newtownabbey63,860 people · ~10 km away
- Lisburn77,506 people · ~11 km away
- Newtownards29,363 people · ~13 km away
- Carrickfergus29,208 people · ~17 km away
- Bangor61,011 people · ~17 km away
FAQ
What is the population of Castlereagh?
Castlereagh has a population of 56,679 (city proper, latest official figure via GeoNames), making it the #206 biggest city in United Kingdom.
What region is Castlereagh in?
Castlereagh is located in Northern Ireland, United Kingdom.
Is Castlereagh the capital of United Kingdom?
No, the capital of United Kingdom is London, about 514 km away.
Sources & notes
Population refers to the city proper (municipal boundaries), not the metropolitan area. Source: GeoNames (CC BY 4.0), retrieved 2026-07-07. Country data: UN World Population Prospects 2024.
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