Herblay-sur-Seine is younger than 90% of compared French towns: a median age of 37.3
With households headed by a retired person at 20%, Herblay-sur-Seine is behind 94% of compared French towns on that count. Census day 2023: 31,779 residents and 12,020 households here. Put another way, about one in four: 28% of households are one person living alone. 0.7% of homes are second homes, fewer than in 92% of compared French towns.
Throughout this page, the Val-d'Oise median and the France median are the median of compared communes (those with an overall grade), each figure its own median. Source: INSEE, census 2023.
What stands out about the people of Herblay-sur-Seine
A town of families
36% of households are couples with children and 15% single parents with children; 22% of residents are under 15. Households ↓
A young town
Half of Herblay-sur-Seine’s residents are under 37.3 and half over; the median of compared French towns is 44. 22% are under 15 and 13% are 65 or older. Ages ↓
Growing fast
Herblay-sur-Seine had 26,944 residents at the 2012 census and 31,779 in 2023, up 18%: faster growth than in 87% of compared French towns. Population ↓
Written from INSEE’s census 2023 on this page, against compared French towns.
Faster growth than 87% of compared French towns: Herblay-sur-Seine changed by +18% since 2012
Residents at INSEE’s last three censuses, each recast in the 2026 commune boundaries. France has no yearly estimate by commune between censuses.
2012 to 2023
2017 to 2023
The median Val-d'Oise town changed +8% and the median compared French town +5%; here the first five years brought +9% and the next six +8%.
13% of residents are 65 or over, fewer than in 95% of compared French towns
Shares of residents by age at the 2023 census.
Age groups · share of residents
Median age of the 3,798 compared French towns
■ Herblay-sur-Seine 37.3. The median compared French town: 44.
The share of residents aged 15 to 24 tops 85% of compared French towns: 13%. On average, 22% of residents are 65 or over in the typical compared French town.
Women and men · all residents
52% women, 48% men
About 91 men for every 100 women. Median share of women: Val-d'Oise 51.5%, France 51.8%.
Couples with children make up 36% in Herblay-sur-Seine, more than in 94% of compared French towns
A household is everyone who shares a main home (résidence principale). Household types come from INSEE’s fuller sample of a quarter of census forms.
Against the Val-d'Oise median and the France median
Living alone · share
Households average 2.6 people. 15% of households are single parents, a higher share than in 94% of compared French towns. The share of couples with children in the typical compared French town is 25%.
A higher share of empty homes than 76% of compared French towns, at 9.5%
Every home the census counted: main residences, second homes and occasional dwellings (INSEE counts them together), and empty homes. Owning and renting are on Cost of living.
All homes · share of homes
Type of home
Cars per household · share of households
Flats: 45%, above 69% of compared French towns. 16% of households rent social housing (HLM). On households without a car, Herblay-sur-Seine sits higher than 64% of compared French towns: 14%. For empty homes, the comparison in the typical compared French town is 6.7%.
A median standard of living of €30,160 a year
The standard of living (niveau de vie) is a household’s disposable income after taxes and benefits, divided by its consumption units (UC) to allow for its size and make-up: 1 for the first adult, 0.5 for each other person 14 or older, 0.3 for each child under 14.
Medians of compared communes. Source: INSEE, Filosofi 2023.
The midpoint of living standards here is €30,160 a year per consumption unit, higher than in 85% of compared French towns. Some 13.2% of residents fall below the poverty line.
Households headed by a manager or professional make up 24% in Herblay-sur-Seine, more than in 93% of compared French towns
Households by the socio-professional group (PCS) of their reference person, INSEE’s own categories. Jobs and commuting are on the Work & commute page.
Households by reference person’s group · share of households
Against a figure of 14% in the typical compared French town, the share of households headed by a manual worker in Herblay-sur-Seine comes in at 9.4%.
Each household is counted once, by the occupation of its reference person (usually the oldest working adult).
More immigrants than 84% of compared French towns: 15%
INSEE publishes two measures, which overlap but aren’t the same. Neither is the UK’s “born abroad”.
Share of residents · census 2023
Immigrant (immigré)
Born abroad, not French at birth. Someone stays an immigrant after becoming French. A French citizen born abroad (for example in Algeria before 1962) is not one.
Foreign national (étranger)
Not a French citizen today, wherever born. A child born in France to foreign parents can be a foreign national without being an immigrant.
The share of foreign nationals tops nearly four fifths of compared French towns: 9.1%. Elsewhere, 6.5% of residents are immigrants in the typical compared French town.
INSEE publishes no country of birth or ethnicity by commune in these tables, and the census doesn’t ask about religion.
In Herblay-sur-Seine, 29% of residents 15 and over are single, more than in 75% of compared French towns
Residents 15 and over by how they live: the census asks both the legal status and whether people live as a couple.
Residents 15 and over · share
Here 44% of residents 15 and over are married, where the figure in the typical compared French town is 43%. For single residents, the comparison in the typical compared French town is 25%.
Herblay-sur-Seine ranks above 87% of compared French towns on graduates of higher education: 45%
Highest diploma of residents 15 and over who have left education, in French terms: the levels don’t map one-to-one to UK or U.S. ones.
Highest diploma · 15 and over, out of education
Nearly a fifth of adults out of school have no qualification in the typical compared French town, against 15% in Herblay-sur-Seine. Across the comparison, 30% of adults out of school hold a higher-education qualification in the typical compared French town.
41 French towns of 30,063 to 33,464 people: this is the 10th youngest
The 40 compared French towns nearest in population, by median age. Hover for each one’s second homes and immigrants; click for its page.
The youngest is Savigny-le-Temple (33.4), the oldest Aix-les-Bains (48.5).
Older than Herblay-sur-Seine: 3 of the 6 towns nearby
The nearest towns of 2,500 or more, colored by median age. Source: INSEE, census 2023.
| Town | Median age | 65+ | Second homes | Immigrants |
|---|---|---|---|---|
| Herblay-sur-Seine | 37.3 | 13% | 0.7% | 15% |
| Pierrelaye 10,130 · 1.6 mi | 35.2 | 12% | 0.8% | 20% |
| La Frette-sur-Seine 4,570 · 1.9 mi | 42.4 | 18% | 1.3% | 12% |
| Montigny-lès-Cormeilles 22,457 · 2 mi | 34.9 | 13% | 0.7% | 24% |
| Beauchamp 9,849 · 2.2 mi | 40.5 | 19% | 1.2% | 17% |
| Conflans-Sainte-Honorine 36,958 · 2.4 mi | 39.1 | 16% | 1.3% | 17% |
| Éragny-sur-Oise 18,436 · 2.8 mi | 35.9 | 14% | 0.8% | 17% |
Health, work, housing and schools
What this data can and can’t tell you
- Census 2023. INSEE’s census is a rolling survey: a fifth of small communes each year, 8% of homes in large ones each year. “2023” pools the surveys of 2021 to 2025, so the figures describe the town around 2023, not on one day.
- Medians of compared communes. The comparisons are the median of the département’s compared communes and of France’s (those with an overall grade), each figure its own median: not the total for the département or for France, which large cities pull towards their own figures.
- Immigrants and foreign nationals. INSEE’s two measures: an immigrant was born abroad without French nationality; a foreign national isn’t French today. Neither is a count of people born abroad, which INSEE doesn’t publish by commune.
- Second homes. Homes used for holidays or weekends, with occasional dwellings (kept for work, for example), which INSEE counts together. Their owners are counted where they live, not here.
- Standard of living. INSEE’s Filosofi: disposable income per consumption unit, from tax and benefit files, 2023. The poverty rate is the share of residents below 60% of France’s median. Not published for the smallest communes.
- What France doesn’t ask. The French census asks nothing about ethnicity, religion, language or health, so this page has no such section.
Questions about who lives in Herblay-sur-Seine
What is the population of Herblay-sur-Seine?
31,779 at INSEE’s 2023 census, 18% more than in 2012 (26,944).
How old are Herblay-sur-Seine’s residents?
The median age is 37.3, younger than 90% of compared French towns. 26% are under 18 and 13% 65 or older.
How many second homes are there in Herblay-sur-Seine?
88, with occasional dwellings: 0.7% of all homes, against 2.1% for the median compared French town.
How many immigrants live in Herblay-sur-Seine?
INSEE counts 4,630 immigrants (born abroad, not French at birth), 15% of residents, and 2,890 foreign nationals (9.1%). The medians of compared French towns are 6.5% and 4.3%.
What is the median income in Herblay-sur-Seine?
€30,160 a year per consumption unit in 2023 (median of compared French towns €25,970); 13.2% of residents live below the poverty line. Source: INSEE, Filosofi.
Sources: INSEE, census 2023 (population, ages, households, homes, marital status, diplomas, immigrants, foreign nationals, employment), 2026 geography · INSEE, Filosofi 2023 (standard of living, poverty) · IGN Admin Express (boundaries) · Medians and percentiles: TownRatings, over compared French towns, updated November 9, 2026. Under the Licence Ouverte / Open Licence 2.0 (Etalab).
Contains public sector information under the Licence Ouverte / Open Licence 2.0 (Etalab): INSEE, DGFiP, the Interior Ministry’s statistics service (SSMSI), the Ministry of Education (DEPP), the Health Ministry’s statistics service (DREES) and the Housing Ministry (Carte des loyers). Commune boundaries: IGN Admin Express.