About one in four city residents worldwide, more than 1.16 billion people, live in slums and informal settlements without safe water, sanitation, enough space, a durable home or secure tenure, and their number grew by more than 130 million between 2015 and 2024.
Updated October 15, 2026. Written from the sources listed below, not independently peer-reviewed.
Out of every 100 people living in cities in sub-Saharan Africa, how many live in slums or informal settlements?
1.16 billion
People living in slums and informal settlements
More than 1.16 billion people in 2024, an increase of over 130 million since 2015. This is a modelled global estimate built from census and household survey data.
Data year 2024. Source: UN-Habitat, 2026
24.8%
Share of the world's city residents living in slums
About one in four urban residents in 2024, down from 30.6% in 2000 but only slightly lower than the 25.3% of 2015. In sub-Saharan Africa the share was 49.4%.
Data year 2024. Source: UN-Habitat, 2026
Nearly 45%
Households spending more than 30% of income on housing
Nearly 45% of households worldwide spend more than 30% of their income on housing costs, with 55% in sub-Saharan Africa. UN-Habitat treats the 30% threshold as an indicative measure only.
Data year 2026. Source: UN-Habitat, 2026
Unit: % of urban population
UN-Habitat global estimates for SDG indicator 11.1.1 as reported in the SDG 11 Global Report 2026. The share has barely changed since 2015, while the absolute number of people living in slums rose by more than 130 million over the same period because urban populations grew.
SDG target 11.1 aims to ensure access for all to adequate, safe and affordable housing and basic services and to upgrade slums by 2030. Indicator 11.1.1 is the only SDG 11 indicator with enough data to estimate the distance to the target, and UN-Habitat finds that relatively little progress has been made since 2015: the share of city residents in slums fell only from 25.3% to 24.8% between 2015 and 2024, while the number of people living in slums rose to more than 1.16 billion.
In sub-Saharan Africa, 49.4% of city residents lived in slums in 2024, compared with 0.3% in Europe and Northern America. More than 56 million people were added to the region's slum population in the last decade alone.
Source: UN-Habitat, 2026In Eastern and South-Eastern Asia the share of city residents in slums fell from 35.5% in 2000 to 24.9% in 2024, yet the number of people grew by more than 46 million in the past decade to almost 377 million. In Central and Southern Asia the share was 42.6% in 2024.
Source: UN-Habitat, 2026Pressure on housing is often greatest for groups already pushed to the margins, including older people, young people, people working informally, refugees and migrants, who may also face discrimination, insecure tenure and barriers linked to documents.
Source: UN-Habitat, 2026UN-Habitat describes the position of informal settlement residents and informal workers as a double climate injustice: they are among the most exposed to disasters and other climate impacts, but are often left out of urban adaptation plans.
Source: UN-Habitat, 2024Each country is shaded by its latest available value, so you can see where the gap is widest. Hover or tap a country, search for one, or open the full table.
Loading country values…
Values in % of urban population.
Share of each country's urban population living in households that lack an improved water source, improved sanitation, enough living space, a durable dwelling or secure tenure, as estimated by UN-Habitat. Values are the latest year available per country (years differ: 2022 for most, 2018 to 2020 for a few; older values are not shown), so they are not directly comparable with UN-Habitat's 2024 global estimates. Several countries share identical values, which suggests regional estimates were used where national data are missing, so treat small differences with caution.
Source: UN-Habitat Urban Indicators Database, via World Bank Open Data. Latest year available per country; years differ.
Values load from World Bank Open Data. Simplified Natural Earth borders; they imply no position on disputed territories.
Instead of one “percent solved” score, DO GOOD rates three separate dimensions. A problem can have mature solutions that still reach too few people. These ratings are an editorial reading of the sources on this page, not a measured index.
Has the situation improved in the real world?
LowThe share of city residents living in slums has hardly moved since 2015, from 25.3% to 24.8% in 2024, and the absolute number grew by more than 130 million, faster than in the decade before.
How mature and validated are the available solutions?
ModerateSome components of upgrading have solid evaluations, such as cement floors in Mexico and land titling in Argentina, but a Cochrane review of slum upgrading found only five studies for its main analysis and rated the evidence of low or very low quality.
How widely are effective solutions actually used?
LowUpgrading has not kept pace with urban growth, and UN-Habitat reports that many cities lack the fiscal space and technical capacity to act at scale. Only about 1% of tracked urban climate finance in 2021–22 went to adaptation, which is where most informal settlements' needs lie.
Indicator 11.1.1 is built from censuses and household surveys and has enough data for a global trend, but country estimates are infrequent, tenure is hard to measure, and some countries' figures appear to be shared regional values.
The share of city residents in slums is still falling slowly in most regions, but because cities are growing, the number of people living in slums is rising, by more than 130 million between 2015 and 2024.
Most people who live in slums and informal settlements have a home, but not an adequate one. UN-Habitat counts an urban household as a slum household if it lacks at least one of five things: an improved water source, improved sanitation, enough living space, a durable dwelling or secure tenure. By this measure, more than 1.16 billion people lived in slums and informal settlements in 2024. The share of city residents affected has fallen slowly, from 30.6% in 2000 to 24.8% in 2024, but because cities are growing quickly, the absolute number rose by more than 130 million after 2015, almost twice the roughly 70 million added in the decade before. UN-Habitat estimates that at least 3 billion people live in inadequate housing when affordability and other aspects of adequacy are also considered. This page covers inadequate housing in cities; people without any home are covered on the homelessness page.
The problem is concentrated in sub-Saharan Africa, where about half of all city residents live in slums, and in South and East Asia, which together are home to hundreds of millions of slum residents. Informal settlements are among the places most exposed to disasters and other climate impacts, many lack basic infrastructure such as energy, water and sanitation, and their residents are often left out of cities' climate adaptation plans. Without secure tenure, households risk eviction and have little reason to invest in improving their homes. Housing costs add to the pressure: nearly 45% of households worldwide spend more than 30% of their income on housing, and older people, young people, informal workers, refugees and migrants are often hit hardest.
SDG indicator 11.1.1 measures the proportion of the urban population living in slums, informal settlements or inadequate housing. It is calculated from population censuses and national household surveys such as DHS and MICS, using the following definitions:
Five household deprivations
A slum household is one whose members lack at least one of the following: access to an improved water source, access to improved sanitation, sufficient living area, a durable dwelling, or security of tenure. A household has sufficient living area when no more than three people share a habitable room.
Informal settlements
Informal settlements are areas where residents have no security of tenure over the land or dwellings they live in. The term is often used as a synonym for slums, and the indicator treats the two together.
Inadequate housing and affordability
The wider concept of inadequate housing also counts homes that are not affordable: a household is considered cost-burdened when its net monthly housing costs exceed 30% of its total monthly income. UN-Habitat stresses that this threshold is indicative rather than a universal standard for every region.
Tenure is the hardest part to measure
The relationship between tenure, land and property is complex, which makes security of tenure difficult to capture in surveys even though it is a core part of the definition. Tenure data are therefore scarcer than data on water, sanitation or crowding.
What works
Improving settlements where they are, with residents involved in decisions, can bring water, sanitation, drainage, paved roads, public space and secure tenure without moving people away from their jobs and social networks. UN-Habitat calls for participatory, rights-based upgrading, and countries such as South Africa have built in-situ upgrading into national and local implementation systems.
Limits
A Cochrane review found only five studies of sufficient quality for its main analysis; the evidence that upgrading reduces diarrhoeal disease and water costs is limited but consistent, while one randomised trial and two controlled studies found no effect on income. Upgrading also needs local capacity and finance that many cities lack, and poorly designed projects can push residents out.
What works
Connecting homes to water and sewer networks removes two of the five slum deprivations directly. In one controlled study in the Cochrane review, households that received water connections from a private water company had about half the incidence of diarrhoea (risk ratio 0.53) and paid 17 pesos less a month for water.
Limits
The confidence interval for the diarrhoea effect was wide and included no effect, the study had a moderate risk of bias, and one study found no change in sanitation-related mortality. Network connections are hard to provide where tenure is disputed or plots are irregular.
What works
Small physical upgrades can have large effects. Mexico's Piso Firme programme replaced dirt floors with up to 50 square metres of cement, worth about US$150 per household. Compared with similar households in a neighbouring city not yet reached, children in areas offered the programme had 19.6% fewer parasitic infections, 12.8% less diarrhoea and 20.1% less anaemia, and adults reported higher satisfaction with their housing and quality of life and lower depression and stress scores.
Limits
The study was not randomised and relied on a single survey in 2005 comparing two neighbouring cities. The authors caution that results may not hold in rural areas, in households without safe water or among undernourished children, and there was no effect on children's height or weight.
What works
Formal rights to land give households protection against eviction and a reason to invest. In a natural experiment in a settlement near Buenos Aires, families who received titles in 1989 had better homes years later than neighbouring families whose titles came years later: the share with good-quality walls was about 40% higher and with good roofs about 47% higher, households were smaller, and children completed more years of school.
Limits
Titling did not improve access to credit in a meaningful way, with only about 4% of early-titled households ever receiving a mortgage, and it had no measurable effect on household income or employment. Results come from one settlement in Argentina, and titling elsewhere may be harder where land claims are disputed or held under customary systems.
What works
A supply of affordable homes, including regulated social and public rental housing, reduces the pressure that pushes people into informal settlements. Vienna has around 220,000 municipal flats and roughly 200,000 subsidised dwellings, and about half of its residents live in municipal or subsidised homes. UN-Habitat notes that housing finance can be expanded through subsidies, refinancing institutions, public investment and regulated social housing providers.
Limits
Such systems take decades and steady public investment to build, and few low-income cities have the fiscal space or land administration to replicate them. Housing has become less affordable overall: the global ratio of house prices to incomes rose from 9.3 in 2010 to 11.2 in 2023.
Promising, but not proven at scale. The stage shows how far each approach has come; it is not a recommendation.
Improved census methods make it possible to locate and count informal settlements rather than estimate them. Brazil's statistics office IBGE mapped 12,348 favelas and urban communities, home to 16.4 million people in 656 municipalities. Few countries produce data at this level of detail, and UN-Habitat notes that globally representative urban data are often too infrequent.
UN-Habitat's World Cities Report 2024 presents upgrading led by residents' own organisations as a way to build resilience to floods, heat and other climate shocks while improving housing and services. Experience is spread across many local projects, and there is little comparable evidence on how well they reduce climate losses.
Cities need an estimated US$4.5 to 5.4 trillion a year for climate-resilient infrastructure, but only about US$10 billion of the US$831 billion in tracked urban climate finance in 2021–22 went to adaptation. Efforts to direct more of this money to the most exposed neighbourhoods, and to include residents in adaptation planning, are still at an early stage.
Implementation gap
More than 130 million people were added to the global slum population between 2015 and 2024, nearly twice the roughly 70 million added in the decade before. Upgrading programmes that work locally have not been scaled to match this growth.
Implementation gap
Nearly 45% of households worldwide spend more than 30% of their income on housing, and the global ratio of house prices to incomes rose from 9.3 in 2010 to 11.2 in 2023. When formal housing is out of reach, informal settlements are often the only option for people on low incomes.
Coordination gap
Residents without secure tenure are often unable to invest in improving their homes because they fear eviction, and protective infrastructure built without them in mind can expose them to eviction or greater risk. Many residents are also left out of the adaptation plans that decide where protective infrastructure goes.
Implementation gap
Cities receive less than 20% of the finance needed for effective climate action, and adaptation received only about 1% of tracked urban climate finance in 2021–22. Many cities also lack the fiscal space and technical capacity to upgrade settlements at scale.
Knowledge gap
The Cochrane review of slum upgrading found high risk of bias, very different interventions and large gaps: no studies on non-communicable diseases or social capital, and only single studies on outcomes such as education, crime or quality of life.
Knowledge gap
Slum estimates rely on censuses and household surveys carried out every few years, tenure security is hard to capture in surveys, and data broken down by settlement, gender, age or disability are scarce. This makes it hard for cities to target programmes and to track whether they work.
Unresolved questions, not vetted breakthroughs. Answering any of them would change what is possible.
Upgrading combines water, sanitation, roads, drainage, housing and tenure. Which components, in which order, bring the largest improvements in health and income, and what do they cost per household?
When settlements are improved, rising land values can push low-income residents out. Which tenure, rent and planning safeguards keep the original residents in place over the long term?
Is a full individual land title necessary, or can cheaper forms of recognition, such as occupancy certificates or collective rights, give households the same security and willingness to invest?
Many informal settlements sit on flood-prone or hot land. When is it better to protect a settlement in place, and when is relocation unavoidable, and how can residents take part in that decision?
Speak of residents of informal settlements rather than using labels that blame people for where they live. UN-Habitat calls for treating residents as co-producers of solutions, not passive beneficiaries.
If you donate or volunteer, consider groups in which residents of informal settlements take part in decisions, and ask how many households gained water, sanitation, better homes or secure tenure.
Affordability is a problem in cities everywhere. Supporting affordable and social housing in local planning decisions is one way to influence how housing is provided in your own city.
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UN-Habitat, published 2026
UN-Habitat's 2026 progress report on SDG 11: more than 1.16 billion people in slums and informal settlements in 2024, global and regional slum shares for 2000, 2015 and 2024, housing cost burdens and price-to-income ratios, groups most affected, examples from Brazil, South Africa and Vienna, and recommendations on participatory upgrading and housing finance. Headline figures also appear in the companion Key Facts and Messages.
UN-Habitat, published 2024
Climate exposure of informal settlements, tenure insecurity and eviction risk, community-led upgrading, projected urban heat and flood exposure, and the gap between urban climate finance needs and flows, including the small share going to adaptation.
UN Statistics Division / UN-Habitat, published 2021
Official definition of slum households (five deprivations, no more than three people per room), informal settlements and inadequate housing (30% affordability threshold), data sources (censuses, DHS, MICS) and the difficulty of measuring tenure; last updated December 2021.
Cochrane Database of Systematic Reviews (Turley et al.), published 2013
Systematic review of slum upgrading in low- and middle-income countries (5 studies in the main analysis, 9 supporting): effects on diarrhoea, water-borne disease, water spending, income and employment, with low to very low quality evidence.
American Economic Journal: Economic Policy (Cattaneo, Galiani, Gertler, Martinez and Titiunik), published 2009
Evaluation of Mexico's Piso Firme programme, which replaced dirt floors with cement: effects on children's parasitic infections, diarrhoea, anaemia and cognitive development and on adults' satisfaction, depression and stress, with limitations.
Galiani and Schargrodsky, CEDLAS Working Paper 103 (published in the Journal of Public Economics, 2010), published 2010
Natural experiment in a settlement in San Francisco Solano, Buenos Aires Province, where titles were granted to some squatter families and delayed for others: effects on housing investment, household size, schooling, credit and income.