Photo: Jaggery · CC BY-SA 2.058% of residents said they have no religion, a share 99% of UK towns don’t reach
With a median age of 39.5, Ystrad Mynach is younger than 83% of UK towns. Across Ystrad Mynach, 32% of households have dependent children. The 2021 Census counted 11,856 residents in 4,898 households. Households average 2.4 people, against 2.3 across Wales’s towns.
What the Census says about Ystrad Mynach’s people
More with no religion than most
58% of residents answered “no religion” in 2021 and 35% Christian, against 47% and 43% across Wales’s towns. Ethnicity & religion ↓
Written from the data on this page: ONS Census 2021 (output areas summed to the 2022 built-up area) and ONS mid-year population estimates.
Slower than most: +4% since 2011, behind 64% of UK towns
ONS mid-year estimates, each year indexed to mid-2011 = 100. Ystrad Mynach’s figure is the small areas (2021 LSOAs) that make up the town.
People, mid-2011 = 100
Change by age, 2011 to 2024
About 12,100 people in 2011; 12,600 in 2024.
Between mid-2012 and mid-2013 the population rose by 160, its biggest one-year gain. Of the age groups, 65 and over changed most (+26%) and 16 to 29 least (−7%).
A smaller share of residents aged 65 and over than 86% of UK towns: 16%
Share of residents in each five-year age band, Census 2021.
In Ystrad Mynach, 11% of residents are aged 15 to 24, beside 12% across Wales’s towns. On average, 21% of residents are 65 or over across Wales’s towns. More residents are 35–39 than any other five-year age: 7.6% of residents.
Median age of UK towns of 2,500+
■ Ystrad Mynach, 39.5. The typical town is 44.4.
Broad ages · share of residents
Women and men · all residents
51% women, 49% men
About an even split. Across Wales, 51% of residents are women.
5.8% of residents lived at another address a year earlier, below 98% of UK towns
What adults did at the 2021 Census (the ONS’s NS-SEC classes), and where residents lived a year earlier.
Adults by occupation class · residents 16 and over
Address a year before the Census
Residents who lived somewhere else a year earlier. The bar runs to 25%.
With full-time students at 5.9%, Ystrad Mynach is ahead of 82% of UK towns on that count. The usual figure: 9.1% of residents lived at another address a year earlier across Wales’s towns.
The Census was taken on 21 March 2021, in term time, so students were counted at their term addresses.
One-person households make up 28% in Ystrad Mynach, less than in 66% of UK towns
Household make-up at the 2021 Census. Each square is 1% of households.
Against Gwent’s towns and Wales’s towns
People per household
Wales’s towns.
Ystrad Mynach sits close to the norm on shared households of unrelated adults: 2.2%, about the same as across Wales’s towns. The comparison figure for one-person households is 32% across Wales’s towns.
Few flats: only 7.6% of households in Ystrad Mynach live in one
Accommodation type and cars or vans per household, Census 2021. Owning and renting are on Cost of living.
Type of home
Cars or vans · share of households
Households without a car or van make up 17%, against 21% across Wales’s towns. Elsewhere, 14% of households live in a flat or apartment across Wales’s towns. Just over a fifth of households live in a terraced house. Fewer households in detached houses than in two thirds of UK towns: 23%.
Only 3% of Ystrad Mynach’s residents were born outside the UK
Country of birth, year of arrival and main language, Census 2021.
Born outside the UK, by region · share of all residents; the bar runs to 10%
When those born abroad arrived
Main language · residents aged 3 and over
Among those born abroad, the share arriving in 2017 or later is 11% (Wales’s towns: 23%). Residents whose main language is English account for 99%. The share of residents born outside the UK across Wales’s towns is 7.4%.
Ystrad Mynach’s Welsh speakers make up 13% of residents
Welsh language skills, residents aged 3 and over, Census 2021.
Welsh language skills · residents aged 3 and over
Asked in 2021, 1,544 residents aged 3 and over, 13%, said they can speak Welsh; across Welsh towns, 16%: more than in 61% of Welsh towns. Abertridwr and Senghenydd leads Gwent with 14%.
Ystrad Mynach ranks below 97% of UK towns on residents who describe themselves as Christian: 35%
How residents described themselves at the 2021 Census. Lines join the lowest and highest of the three figures.
Ethnic groups other than White British · all residents
White British, not charted: 96% of Ystrad Mynach · Gwent’s towns 91% · Wales’s towns 90%.
Religion · all residents
The figure for residents who describe themselves as White British is 96% in Ystrad Mynach and 90% across Wales’s towns. Besides White British, the main groups are Other White (1.3%), Mixed or multiple (1.3%) and Indian (0.3%). Residents who describe themselves as Christian: 43% across Wales’s towns, for comparison.
Ystrad Mynach ranks below 70% of UK towns on married adults and civil partners: 45%
Legal partnership status (residents 16 and over) and unpaid care (residents 5 and over), Census 2021.
Partnership status · residents 16 and over
Unpaid care given · share of residents 5 and over
Heavy unpaid care, 50 hours a week or more, falls to 489 residents. Higher than in 86% of UK towns: 11% of residents give unpaid care. Typically, 43% of adults are married or in a civil partnership across Wales’s towns. Adults who have never married: 37% here and 38% across Wales’s towns.
30% of adults have a degree-level qualification
Highest qualification, residents 16 and over, Census 2021.
Highest qualification · residents 16 and over
With 30% of its adults qualified to degree level, Ystrad Mynach compares with 31% across Wales’s towns; another 21% hold no qualification (20%).
From a median age of 38 in Hengoed & Maesycwmer to 43 in St Cattwg
The town’s 3 neighbourhoods (ONS middle-layer areas with 500+ residents inside it, named by the House of Commons Library), youngest first. Census 2021.
St Cattwg is the oldest area, with 20% aged 65 or over; Hengoed & Maesycwmer the youngest (median age 38). Families with children are most common in Hengoed & Maesycwmer (34% of households).
45th lowest median age among 432 UK towns of 8,000 to 16,000
Median age, Census 2021. Hover a dot for its students and residents born abroad; click for its page.
The youngest is Aberystwyth (25) and the oldest Sidmouth (60.4). Nearest to Ystrad Mynach in age: Holyhead (39.4), South Kirkby (39.5), Thurnscoe (39.6) and Harworth and Bircotes (39.6).
6 of the 7 nearest towns are older than Ystrad Mynach
Nearby built-up areas coloured by median age, Census 2021. Tap a town for its page.
| Town | People | Away | Median age | 65+ | Homes with children |
|---|---|---|---|---|---|
| Ystrad Mynach | 11,856 | — | 39.5 | 16% | 32% |
| Maesycwmmer | 2,095 | 0.6 mi | 46.1 | 24% | 25% |
| Fleur-de-lis and Pengam | 3,102 | 1.2 mi | 44.4 | 21% | 28% |
| Tir-y-berth and Glan-y-nant | 1,411 | 1.2 mi | 39.9 | 17% | 32% |
| Pen-pedair-heol | 3,787 | 1.3 mi | 46.9 | 23% | 25% |
| Gelligaer | 1,436 | 1.4 mi | 36.5 | 16% | 32% |
| Blackwood | 12,621 | 1.8 mi | 45.5 | 23% | 27% |
| Pontllanfraith | 9,363 | 1.8 mi | 43.5 | 22% | 27% |
Health, work and homes have their own pages
What this data can and can’t tell you
- The Census was taken in a lockdown, in term time. 21 March 2021 fell in term time, and students were asked to give their term-time address, so most were counted where they study. Some may have been living with family that day.
- “Gwent’s towns” and “Wales’s towns” mean their built-up areas. Census comparisons pool every built-up area in Gwent (or Wales), summed the same way as Ystrad Mynach’s figures, so households in open countryside are left out. The population trend compares with the whole county and nation.
- Estimates since 2021 are modelled. The ONS builds mid-year estimates from the Census, births, deaths and migration records. Ystrad Mynach’s trend uses the small areas (2021 LSOAs) with most of their people inside it: 12,395 people in 2021, against 11,856 in the built-up area.
- Small counts are blurred. The ONS adds small random changes to Census counts to protect privacy, so the same total differs a little between tables, and the shares of a small town can move by a point or two.
Questions about Ystrad Mynach’s residents
What is the population of Ystrad Mynach?
The 2021 Census counted 11,856 people in Ystrad Mynach’s built-up area. The ONS estimates the same small areas held 12,600 people in mid-2024, 4% more than in 2011.
What is the average age in Ystrad Mynach?
The median age was 39.5 at the 2021 Census, younger than 83% of UK towns. 11% of residents were 15 to 24 and 16% were 65 or over.
How diverse is Ystrad Mynach?
96% of residents described themselves as White British in 2021, against 90% across Wales’s towns and 91% across Gwent’s towns. 3% were born outside the UK.
What religion are people in Ystrad Mynach?
58% said they had no religion and 35% that they were Christian at the 2021 Census; 0.6% were Muslim and 6.1% didn’t answer.
Is Ystrad Mynach good for families?
32% of households had dependent children in 2021, against 27% across Wales’s towns. Families are most common in Hengoed & Maesycwmer (34% of households). Schools are on Ystrad Mynach’s schools page.
How many people speak Welsh in Ystrad Mynach?
1,544 residents aged 3 and over, 13%, said they can speak Welsh at the 2021 Census, against 16% across Welsh towns.
Sources: ONS Census 2021, output areas summed to the ONS 2022 built-up area (TS002, TS003, TS004, TS007A, TS008, TS015, TS017, TS019, TS021, TS029, TS030, TS039, TS044, TS045, TS062, TS067, TS032) · ONS mid-year population estimates for 2021 LSOAs, mid-2011 to mid-2024 · House of Commons Library MSOA names. All under the Open Government Licence v3.0.
Contains public sector information licensed under the Open Government Licence v3.0. Contains HM Land Registry data © Crown copyright and database right 2026. Contains OS data © Crown copyright and database right 2026 (ONS boundaries). Northern Ireland: Source: NISRA; contains Land & Property Services data and Ordnance Survey of Northern Ireland information, © Crown copyright, licensed under the Open Government Licence v3.0. Scotland: contains National Records of Scotland data, Registers of Scotland data and SEPA data, © Crown copyright / © SEPA 2025, licensed under the Open Government Licence v3.0.