# Castle B3 North Belfast. 416 people (mid-2024 estimate) in 0.1 square kilometres. Castle B3 had 438 usual residents at the census (NISRA Census 2021). Neighbourhood. Code N20000792. In: [Northern Ireland](https://openindex.co.uk/northern-ireland) › [Belfast](https://openindex.co.uk/belfast) ## Key figures - **Population: 438** (2021). Castle B3 had 438 usual residents at the census (NISRA Census 2021). Joint 1,477th least populated of 46,844. Source: Census 2021, England and Wales and Scotland's Census 2022 and Census 2021, Northern Ireland, 2021. Published 21 July 2026. https://openindex.co.uk/belfast/neighbourhood/n20000792#f-population - **Gigabit broadband coverage: 100.0%** (January 2026). In Castle B3, 100.0% of homes and businesses could get gigabit-capable broadband in January 2026 (Ofcom). UK 87.8%. Source: Connected Nations (Ofcom), January 2026. Published 13 May 2026. https://openindex.co.uk/belfast/neighbourhood/n20000792#f-gigabit-coverage - **Aged 15 to 64: 69.5%** (2021). 69.5% of residents in Castle B3 were aged 15 to 64 at the census (NISRA Census 2021). Joint 7,379th highest of 46,844. Source: Census 2021, England and Wales and Scotland's Census 2022 and Census 2021, Northern Ireland, 2021. Published 21 July 2026. https://openindex.co.uk/belfast/neighbourhood/n20000792#f-age-15-to-64 - **Aged 65 and over: 10.5%** (2021). 10.5% of residents in Castle B3 were aged 65 or over at the census (NISRA Census 2021). Joint 7,635th lowest of 46,844. Source: Census 2021, England and Wales and Scotland's Census 2022 and Census 2021, Northern Ireland, 2021. Published 21 July 2026. https://openindex.co.uk/belfast/neighbourhood/n20000792#f-age-65-and-over ## On the map - [Gigabit coverage by neighbourhood](https://openindex.co.uk/map/gigabit-broadband?place=N20000792) (Connected Nations (Ofcom) · January 2026): In Castle B3, 100.0% of homes and businesses could get gigabit-capable broadband in January 2026. - [Average house price by council](https://openindex.co.uk/map/house-prices?place=N20000792) (UK House Price Index · August 2026): Published for whole councils, so the map colours all of Belfast. The outline is Castle B3. - [Crime and ASB by neighbourhood](https://openindex.co.uk/map/recorded-crime?place=N20000792) (Police recorded crime and outcomes (data.police.uk) · August 2026): Police recorded 0 crimes and anti-social behaviour incidents in Castle B3 in August 2026. - [Population by neighbourhood](https://openindex.co.uk/map/population?place=N20000792) (Census 2021, England and Wales): Castle B3 had 438 usual residents at the census. Northern Ireland Multiple Deprivation Measure 2017 is published for the Super Output Areas (2001), whose boundaries differ from this neighbourhood’s, so it has no figure for Castle B3. [See deprivation across Belfast](https://openindex.co.uk/belfast/deprivation) ## How Castle B3 compares Each neighbourhood against every other neighbourhood the measure covers. | Measure | Castle B3 | Rank | Compared with | | --- | --- | --- | --- | | Population | 438 | joint 337th least populated | 735 neighbourhoods, Belfast · 2021 | | Gigabit broadband coverage | 100.0% | joint highest | 735 neighbourhoods, Belfast · Jan 2026 | | Aged 15 to 64 | 69.5% | joint 200th highest | 735 neighbourhoods, Belfast · 2021 | | Aged 65 and over | 10.5% | joint 200th lowest | 735 neighbourhoods, Belfast · 2021 | ## What is the population of Castle B3? Castle B3 had 438 usual residents at the census. Castle B3 is the joint 1,477th least populated of 46,844 in the UK. ## Figures for the whole of Belfast These figures are published for the whole of Belfast, not for each neighbourhood, so they describe all of Belfast and not Castle B3 alone. [See Belfast](https://openindex.co.uk/belfast) - **Average house price: £184,768** (August 2026). Belfast’s average house price was £184,768 in August 2026 (HM Land Registry). Up 7.7% in a year. Source: UK House Price Index, August 2026. Published 21 October 2026. - **Population estimate: 351,927** (2025). Belfast’s population was an estimated 351,927 in mid-2025 (ONS population estimates). Down 0.1% in a year. Source: Mid-year population estimates, 2025. Published 1 October 2026. - **Female life expectancy: 80.5 years** (2022 to 2024). A baby girl born in Belfast could expect to live 80.5 years, based on deaths in 2022 to 2024 (ONS life expectancy). UK 83.0 years. Source: Life expectancy for local areas of the UK, 2022 to 2024. Published 10 December 2025. - **People in radon Affected Area squares: 14%** (2022). About 14% of people in Belfast live in a 1 km square that the radon atlas marks as a radon Affected Area. UK 44%. Source: Worked out by Open Index from the UKHSA and BGS radon atlas and census output areas. Published 1 December 2022. ## Castle B3 in brief Castle B3 had 438 usual residents at the census. In Castle B3, 100.0% of homes and businesses could get gigabit-capable broadband in January 2026. 69.5% of residents in Castle B3 were aged 15 to 64 at the census. 10.5% of residents in Castle B3 were aged 65 or over at the census. ## About - Type: Neighbourhood - Code: N20000792 - Middle area: [Castle B](https://openindex.co.uk/belfast/castle-b) - Ward: [Bellevue †](https://openindex.co.uk/belfast/ward/bellevue) - Constituency: [Belfast North †](https://openindex.co.uk/constituency/belfast-north) - Council: [Belfast](https://openindex.co.uk/belfast) - Nation: [Northern Ireland](https://openindex.co.uk/northern-ireland) - Area: 0.06 km² - People, mid-2024: 416 † Best fit: the ward and constituency this neighbourhood mostly lies in. Its edges do not follow theirs. ## Next door [Castle B4](https://openindex.co.uk/belfast/neighbourhood/n20000793), [Castle C1](https://openindex.co.uk/belfast/neighbourhood/n20000794), [Macedon L4](https://openindex.co.uk/antrim-and-newtownabbey/neighbourhood/n20000210), [Macedon L3](https://openindex.co.uk/antrim-and-newtownabbey/neighbourhood/n20000209), [Castle B1](https://openindex.co.uk/belfast/neighbourhood/n20000790) ## Latest updates for Castle B3 - August 2026 house prices published: HM Land Registry and partners · Oct 2026. - September 2026 rent published: ONS private rents · Oct 2026. - Nitrogen dioxide (NO2) updated: Defra · Oct 2026. - 2025 population published: ONS population estimates · Oct 2026. The same figures as JSON: https://openindex.co.uk/v1/places/N20000792 ## How to cite Source: Open Index, openindex.co.uk. Link to this page, https://openindex.co.uk/belfast/neighbourhood/n20000792, or to one figure with its anchor, https://openindex.co.uk/belfast/neighbourhood/n20000792#f-population. Open Index's own text and the figures it works out are licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source data keeps its publishers' licences, named with each figure. Give each figure's period and source with it. Snapshot 2026.10.9. The HTML page: https://openindex.co.uk/belfast/neighbourhood/n20000792