Photo: Langladure · CC BY-SA 3.0Younger than 96% of compared French towns: half of Guyancourt is under 35.4
Nearly one in ten households are headed by a manager or professional in the typical compared French town, against 27% in Guyancourt. Across Guyancourt, just over three quarters of homes are flats. Few places have as many couples with children: 29% here, more than in 73% of compared French towns. Its 12,350 households held 29,778 residents at the 2023 Census.
Throughout this page, the Yvelines 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 Guyancourt
A young town
Half of Guyancourt’s residents are under 35.4 and half over; the median of compared French towns is 44. 22% are under 15 and 11% are 65 or older. Ages ↓
Social housing
43% of households rent from a social landlord (HLM), 18% rent privately and 37% own their home. Homes & cars ↓
Immigrants
INSEE counts 5,400 immigrants in Guyancourt (people born abroad who weren’t French at birth, whatever their nationality now): 18% of residents, against 15% for the median compared commune in Yvelines. 13% are foreign nationals. Immigrants and foreign nationals ↓
Many graduates
48% of residents 15 and over who have left education hold a diploma above the bac, 23% a master’s or more (bac+5). Qualifications ↓
Written from INSEE’s census 2023 on this page, against compared French towns.
+6% since 2012, a pace 56% of compared French towns didn’t match
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
From 2012 to 2017 the population moved +2%, and from 2017 to 2023 +4%; the median compared French town changed +5% and the median Yvelines town +7%.
Guyancourt ranks below 99% of compared French towns on residents aged 65 and over: 11%
Shares of residents by age at the 2023 census.
Age groups · share of residents
Median age of the 3,798 compared French towns
■ Guyancourt 35.4. The median compared French town: 44.
The figure for residents aged 15 to 24 is 13% in Guyancourt and 11% in the typical compared French town. The wider picture: 22% of residents are 65 or over in the typical compared French town.
Women and men · all residents
51% women, 49% men
About 95 men for every 100 women. Median share of women: Yvelines 51.6%, France 51.8%.
15% of households are single parents, more than in 96% 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 Yvelines median and the France median
Living alone · share
A household here holds 2.4 people on average. Compared with other places, one-person households are common here: 37%, more than in 57% of compared French towns. The usual figure: one in ten households are single parents in the typical compared French town.
43% of households rent social housing (HLM), a share 99% of compared French towns don’t reach
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
Against a figure of 6.7% in the typical compared French town, the share of empty homes in Guyancourt comes in at 4.7%. Meanwhile, on households without a car, Guyancourt sits higher than 76% of compared French towns: 17%. Elsewhere, just over one in ten households rent social housing (HLM) in the typical compared French town. About one in 42: that is how common second homes are in Guyancourt (2.4%).
€27,570 a year: the median standard of living
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 €27,570 a year per consumption unit and half below; the level is higher than in 66% of compared French towns. Below the poverty threshold: 15.1% of the population.
A smaller share of households headed by a retired person than 98% of compared French towns: 18%
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
The share of households headed by a manual worker is 9.9%, against 14% in the typical compared French town. Households headed by a retired person: 32% in the typical compared French town, for comparison.
Each household is counted once, by the occupation of its reference person (usually the oldest working adult).
Guyancourt: 18% of residents are immigrants, above 91% 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.
With foreign nationals at 13%, Guyancourt is ahead of 89% of compared French towns on that count. Immigrants: 6.5% in the typical compared French town, for comparison.
INSEE publishes no country of birth or ethnicity by commune in these tables, and the census doesn’t ask about religion.
35% of residents 15 and over are single, a share 92% of compared French towns don’t reach
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
38% of residents 15 and over are married, against 43% in the typical compared French town. The benchmark for single residents in the typical compared French town: 25%.
Guyancourt sits above 91% of compared French towns for graduates of higher education (48%)
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
Adults with no qualification: 15% here and 19% in the typical compared French town. The comparison figure for graduates of higher education is 30% in the typical compared French town.
The 10th youngest of 41 French towns of 28,496 to 31,188 people
The 40 compared French towns nearest in population, by median age. Hover for each one’s second homes and immigrants; click for its page.
Ages run from 30.5 in Clichy-sous-Bois to 56.2 in Agde.
Around Guyancourt, 5 of 6 towns have a higher median age
The nearest towns of 2,500 or more, colored by median age. Source: INSEE, census 2023.
| Town | Median age | 65+ | Second homes | Immigrants |
|---|---|---|---|---|
| Guyancourt | 35.4 | 11% | 2.4% | 18% |
| Voisins-le-Bretonneux 10,624 · 1.1 mi | 44.9 | 21% | 1.7% | 11% |
| Montigny-le-Bretonneux 32,465 · 1.4 mi | 39.7 | 15% | 2.4% | 16% |
| Saint-Cyr-l'École 21,268 · 2.1 mi | 34.5 | 11% | 3.9% | 18% |
| Buc 5,816 · 2.7 mi | 42 | 20% | 1.7% | 11% |
| Fontenay-le-Fleury 13,680 · 2.8 mi | 38.6 | 17% | 1.9% | 19% |
| Bois-d'Arcy 16,586 · 2.8 mi | 35.9 | 13% | 2.7% | 16% |
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 Guyancourt
What is the population of Guyancourt?
29,778 at INSEE’s 2023 census, 6% more than in 2012 (28,039).
How old are Guyancourt’s residents?
The median age is 35.4, younger than 96% of compared French towns. 27% are under 18 and 11% 65 or older.
How many second homes are there in Guyancourt?
320, with occasional dwellings: 2.4% of all homes, against 2.1% for the median compared French town.
How many immigrants live in Guyancourt?
INSEE counts 5,410 immigrants (born abroad, not French at birth), 18% of residents, and 3,820 foreign nationals (13%). The medians of compared French towns are 6.5% and 4.3%.
What is the median income in Guyancourt?
€27,570 a year per consumption unit in 2023 (median of compared French towns €25,970); 15.1% 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.