A larger share of couples with children than 97% of compared French towns: 37%
Households in social housing are rarer here than in 99% of compared French towns. Census figures put households headed by a retired person at 44% in Lassy. At the 2023 Census, 196 people lived locally, in 81 households. 2.4% of households have no car, against 11% in the typical compared French town.
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 Lassy
A town of families
37% of households are couples with children and 6.2% single parents with children; 21% of residents are under 15. Households ↓
A young town
Half of Lassy’s residents are under 38.1 and half over; the median of compared French towns is 44. 21% are under 15 and 17% are 65 or older. Ages ↓
Written from INSEE’s census 2023 on this page, against compared French towns.
A growing town: +8% since 2012, faster than 64% of compared French towns
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
Younger than 88% of compared French towns: half of Lassy is under 38.1
Shares of residents by age at the 2023 census.
Age groups · share of residents
Median age of the 3,798 compared French towns
■ Lassy 38.1. The median compared French town: 44.
In Lassy, 17% of residents are 65 or over, beside 22% in the typical compared French town. Residents aged 15 to 24 make up about one in eight here (13%).
Women and men · all residents
53% women, 47% men
About 90 men for every 100 women. Median share of women: Val-d'Oise 51.5%, France 51.8%.
A lower share of single-parent households than 95% of compared French towns, at 6.2%
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
Against a figure of 35% in the typical compared French town, the share of one-person households in Lassy comes in at 31%. Single-parent households: 10% in the typical compared French town, for comparison. Households here average 2.4 people each.
Flats make up 21% in Lassy, less than in 67% of compared French towns
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
At 1.7%, the share of second homes is lower than in 58% of compared French towns. By way of comparison, 30% of homes are flats in the typical compared French town. Locally, 6.8% of homes stand empty.
A median of €30,130 a year per consumption unit
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.
Living standards centre on €30,130 a year per consumption unit: higher than in 85% of compared French towns.
Below 93% of compared French towns: 6.2% of households are headed by a manual worker
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
Here nearly a fifth of households are headed by a manager or professional, where the figure in the typical compared French town is 9.4%. Households headed by a manual worker make up 14% in the typical compared French town.
Each household is counted once, by the occupation of its reference person (usually the oldest working adult).
4% of residents are immigrants, fewer than in 73% 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.
The median compared commune in Val-d'Oise has 16%; immigrants here make up a share lower than in 73% of compared French towns. For comparison, 6.5% of residents are immigrants in the typical compared French town. The census found that 3.5% of residents are foreign nationals in Lassy.
INSEE publishes no country of birth or ethnicity by commune in these tables, and the census doesn’t ask about religion.
A higher share of married residents than 81% of compared French towns, at 47%
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 share of single residents tops 80% of compared French towns: 30%. The usual figure: 43% of residents 15 and over are married in the typical compared French town.
Fewer adults with no qualification than 93% of compared French towns: 11%
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
By its share of graduates of higher education (38%), Lassy is above 75% of compared French towns. As a reference point, 19% of adults out of school have no qualification in the typical compared French town.
Among 41 French towns of 196 to 2,582 people, the 2nd 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.
Villejust is the youngest (37.2); Prayssac the oldest (62.3).
Older than Lassy: 5 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 |
|---|---|---|---|---|
| Lassy | 38.1 | 17% | 1.7% | 4% |
| Luzarches 5,008 · 1.7 mi | 40.7 | 17% | 1.9% | 9% |
| Chaumontel 3,332 · 2.2 mi | 44.8 | 21% | 2% | 9.9% |
| Marly-la-Ville 6,022 · 2.7 mi | 38.6 | 15% | 1% | 12% |
| Fosses 10,570 · 2.9 mi | 36.1 | 13% | 0.8% | 21% |
| Coye-la-Forêt 3,915 · 3.3 mi | 44.5 | 20% | 3.2% | 8.8% |
| Puiseux-en-France 3,765 · 3.4 mi | 38.7 | 14% | 0.6% | 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 Lassy
What is the population of Lassy?
196 at INSEE’s 2023 census, 8% more than in 2012 (181).
How old are Lassy’s residents?
The median age is 38.1, younger than 88% of compared French towns. 24% are under 18 and 17% 65 or older.
How many second homes are there in Lassy?
1, with occasional dwellings: 1.7% of all homes, against 2.1% for the median compared French town.
How many immigrants live in Lassy?
INSEE counts 8 immigrants (born abroad, not French at birth), 4% of residents, and 7 foreign nationals (3.5%). The medians of compared French towns are 6.5% and 4.3%.
What is the median income in Lassy?
€30,130 a year per consumption unit in 2023 (median of compared French towns €25,970). 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.