Foundations

Census and demographics

How the Brazilian Institute of Geography and Statistics counts favela populations, what its categories include, and what they consistently miss.

Most of what is known about favela populations at scale comes from the IBGE — the Instituto Brasileiro de Geografia e Estatística — and from research that builds on IBGE data. The agency conducts a decennial census, several continuous household surveys, and a specific mapping of informal settlements. Each instrument has its own definitions and its own limits. Reading favela statistics carefully means knowing which one is being cited.

Aglomerados subnormais: the working category

Since the 1991 census, the IBGE has used the technical category aglomerado subnormal (literally "subnormal cluster") to designate informal settlements meeting specific criteria. The current definition requires at least fifty-one housing units occupying or having recently occupied land owned by others, with construction in a disorderly pattern or lacking essential public services. The category is operational rather than legal: it tells census enumerators which areas to treat as informal settlements, but it does not establish rights or obligations.

Aglomerado subnormal is broader than the everyday Brazilian sense of favela. It covers favelas proper, palafitas (stilt settlements over water), invasões, peripheral irregular subdivisions, and a range of other settlement types. In some regions of Brazil — notably the North and Northeast — the local terminology differs from favela, but the IBGE category captures comparable phenomena.

The 2010 and 2022 rounds

The 2010 census recorded approximately 6,329 aglomerados subnormais nationally, with a combined population of around 11.4 million people, accounting for roughly 6 percent of Brazil's population (IBGE Census 2010). The 2022 census, the first decennial round after a twelve-year gap caused by federal underfunding and the COVID-19 pandemic, used a substantially revised methodology with updated cartography, expanded ground partnerships, and a refined definition. The 2022 release identified roughly 12,348 aglomerados subnormais housing approximately 16.4 million people, or about 8 percent of the population (IBGE Census 2022, preliminary release).

The 2010-to-2022 increase reflects both real growth and methodological change. The IBGE has been explicit that the revised methodology captures settlements that earlier rounds missed, and direct year-on-year comparison is not straightforward.

Continuous surveys

Between censuses, the principal source of household-level data is the Pesquisa Nacional por Amostra de Domicílios Contínua (PNAD Contínua), a continuous household sample survey. PNAD Contínua does not separately identify aglomerados subnormais in published tables, but it provides national, regional, and metropolitan-area data on income, employment, education, and household conditions that researchers cross-reference with census data on informal settlements.

For favela-specific indicators between censuses, research is more often done by civic organizations — Data Favela (a collaboration between the Central Única das Favelas, CUFA, and Instituto Locomotiva), Data_Labe, the Observatório de Favelas — that conduct their own sample surveys within particular communities. These surveys are not nationally representative and use varying definitions, but they capture detail that national instruments do not.

What the census measures well

For the population of identified aglomerados subnormais, the census provides standard demographic indicators: total population, age structure, sex composition, racial self-identification (the IBGE categories of branca, parda, preta, amarela, indígena), household composition, basic housing conditions (number of rooms, building materials, water and sanitation), educational attainment for residents above a certain age, and income from work and pensions. The 2010 round added detailed questions on migration, and the 2022 round added questions specific to informal-settlement conditions.

For the headline social pattern, the census data are consistent. Compared with non-favela urban populations in the same cities, favela residents are younger on average, are disproportionately preta and parda in racial self-identification, have lower formal educational attainment, and report substantially lower household income. The gap with surrounding neighborhoods is large; in Rio's South Zone, where wealthy areas border favelas directly, household-income differences across a single street can be order-of-magnitude.

What the census measures poorly

Several aspects of favela life are systematically under-captured.

Informal income. Census income questions ask about income from work and from public benefits. They do not capture informal economy income well. Reading favela income data without that caveat substantially understates total household resources in many cases.

Property values. The census does not measure the market value of favela housing, and where housing is unregistered, it does not appear in tax-roll data either. This produces a systematic invisibility of household wealth in informal settlements, even where property in well-located favelas transacts at substantial prices.

Population in active conflict zones. Census enumeration in communities under armed-group control or during active police operations is hard. The 2010 round in particular was widely criticized — by Rio residents' associations, the city of Rio's own planners, and academics including Janice Perlman — for undercounting populations in larger Rio favelas. The 2022 round addressed this in part through partnerships with community-based teams.

Mobility. Favela populations include substantial commuting, seasonal, and circulating populations that the census's single-night enumeration method captures imperfectly.

City-level rosters

Several large cities maintain their own rosters of favelas alongside the IBGE data. Rio de Janeiro's Instituto Pereira Passos maintains a detailed favela boundary file used for municipal planning. São Paulo's housing secretariat maintains a similar inventory distinguishing favelas, loteamentos irregulares, and cortiços. These city-level rosters often identify more settlements than the IBGE, because they use looser thresholds for inclusion.

What the demographic profile looks like

Synthesizing across the 2010 and 2022 census releases and the IBGE's 2019 Aglomerados Subnormais classification, the demographic profile of Brazilian favela populations has several stable features:

• The population is concentrated in the Southeast (above all Rio de Janeiro and São Paulo metropolitan areas) and the Northeast (Recife, Salvador, Fortaleza), with substantial communities also in the North (Belém, Manaus).
• Median age is lower than the national urban median, with a younger age structure.
• Self-identified preta and parda residents form a clear majority of the population in most major-city favelas, against a national majority of parda and branca.
• Formal employment rates are lower and informal employment rates are higher than in surrounding neighborhoods.
• Household-size distributions are wider, with both single-occupant households and large multi-generational households more common than in adjacent formal areas.

Why headline numbers vary

Headline national-favela-population figures circulating in journalism vary between roughly 12 million and 17 million people. The variation reflects three things: which census round is being cited; whether the figure refers to IBGE aglomerados subnormais (a narrower category) or to a broader sense of informal-urban-settlement populations including peripheral subdivisions; and whether civic-society estimates that argue for an undercount are being used. None of these figures is wrong; they answer slightly different questions.