Couples with children: 41%, a higher share than 99% of compared French towns
In the typical compared French town, the share of households headed by a retired person is 32%; Fosses has 23%. The census found that 3.7% of homes stand empty here. Higher than in 72% of compared French towns: 18% of households rent social housing (HLM). Census day 2023: 10,570 residents and 3,840 households locally.
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 Fosses
A town of families
41% of households are couples with children and 14% single parents with children; 24% of residents are under 15. Households ↓
Immigrants
INSEE counts 2,200 immigrants in Fosses (people born abroad who weren’t French at birth, whatever their nationality now): 21% of residents, against 16% for the median compared commune in Val-d'Oise. 15% are foreign nationals. Immigrants and foreign nationals ↓
A young town
Half of Fosses’ residents are under 36.1 and half over; the median of compared French towns is 44. 24% are under 15 and 13% are 65 or older. Ages ↓
Written from INSEE’s census 2023 on this page, against compared French towns.
Faster growth than 70% of compared French towns: Fosses changed by +10% 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
Against +5% for the median compared French town and +8% for the median Val-d'Oise town, the change came in two steps: +1% from 2012 to 2017, then +9% to 2023.
Half of Fosses is under 36.1, younger than 94% 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
■ Fosses 36.1. The median compared French town: 44.
With residents aged 15 to 24 at 13%, Fosses is ahead of 90% of compared French towns on that count. Residents aged 65 and over are rarer here than in 97% of compared French towns.
Women and men · all residents
52% women, 48% men
About 93 men for every 100 women. Median share of women: Val-d'Oise 51.5%, France 51.8%.
Fosses ranks below 87% of compared French towns on one-person households: 28%
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
Each household has 2.8 people on average. On average, just over a third of households are one person living alone in the typical compared French town. Compared with other places, single-parent households are common here: 14%, more than in 89% of compared French towns.
Fosses sits below 86% of compared French towns for second homes (0.8%)
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
Households without a car make up 13%, against 11% in the typical compared French town. Put another way, about one in three: 30% of homes are flats. As a yardstick, 2.1% of homes are second homes in the typical compared French town.
The middle resident’s standard of living: €25,610 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.
Half of residents live in households above €25,610 a year per consumption unit and half below; the level is lower than in 53% of compared French towns. The share living below the poverty line is 15.0%.
Fosses ranks above 78% of compared French towns on households headed by a manual worker: 19%
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
12% of households are headed by a manager or professional; in the typical compared French town the figure is 9.4%. Measured more widely, 14% of households are headed by a manual worker in the typical compared French town.
Each household is counted once, by the occupation of its reference person (usually the oldest working adult).
Immigrants make up 21% in Fosses, more than in 94% of compared French towns
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.
15% of residents are foreign nationals (typical compared French town: 4.3%). The usual figure: 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.
Fosses: 32% of residents 15 and over are single, above 85% 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
The census found that 44% of residents 15 and over are married in Fosses. Single residents make up 25% in the typical compared French town.
More adults with no qualification than 61% of compared French towns: 21%
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
Graduates of higher education account for 30%. In the typical compared French town, the share of adults with no qualification is 19%.
Ranked by age, 2nd youngest of 41 French towns this size
The 40 compared French towns nearest in population, by median age. Hover for each one’s second homes and immigrants; click for its page.
Charvieu-Chavagneux is the youngest (35.9); La Londe-les-Maures the oldest (59.6).
Among its 6 nearest neighbors, 5 are older than Fosses
The nearest towns of 2,500 or more, colored by median age. Source: INSEE, census 2023.
| Town | Median age | 65+ | Second homes | Immigrants |
|---|---|---|---|---|
| Fosses | 36.1 | 13% | 0.8% | 21% |
| Marly-la-Ville 6,022 · 0.8 mi | 38.6 | 15% | 1% | 12% |
| Survilliers 4,091 · 1.5 mi | 35.6 | 13% | 1.2% | 14% |
| La Chapelle-en-Serval 3,084 · 2 mi | 38.2 | 12% | 1.9% | 8.6% |
| Orry-la-Ville 3,583 · 2.3 mi | 45.1 | 22% | 2.3% | 7.4% |
| Puiseux-en-France 3,765 · 2.7 mi | 38.7 | 14% | 0.6% | 14% |
| Saint-Witz 2,724 · 2.7 mi | 40.9 | 16% | 0.9% | 14% |
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 Fosses
What is the population of Fosses?
10,570 at INSEE’s 2023 census, 10% more than in 2012 (9,582).
How old are Fosses’ residents?
The median age is 36.1, younger than 94% of compared French towns. 28% are under 18 and 13% 65 or older.
How many second homes are there in Fosses?
34, with occasional dwellings: 0.8% of all homes, against 2.1% for the median compared French town.
How many immigrants live in Fosses?
INSEE counts 2,220 immigrants (born abroad, not French at birth), 21% of residents, and 1,550 foreign nationals (15%). The medians of compared French towns are 6.5% and 4.3%.
What is the median income in Fosses?
€25,610 a year per consumption unit in 2023 (median of compared French towns €25,970); 15.0% 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 4, 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.