Population Size, Growth, Composition and Distribution in India

Demography and the Study of India’s Population

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• Demography is the systematic study of the size, growth, composition, and distribution of human populations, and of the processes — birth, death, migration — that produce change in them. For a sociologist, population is not simply a number but a structured social fact: how many people there are, how they are distributed across age, sex, religion, and region, and how fast these numbers are changing all shape the possibilities for economic development, social welfare, and political organisation.
• India’s population is studied through the decennial Census, the single largest administrative exercise of its kind in the world, supplemented by large-scale sample surveys such as the National Family Health Survey (NFHS) and the Sample Registration System (SRS), which provide more frequent, if less exhaustive, updates between census years.
• Because India last held a full Census in 2011 — the 2021 Census was postponed first by the COVID-19 pandemic and then by administrative delay — most of the granular composition and distribution data available today is still drawn from that 2011 count, even as the country’s total size is now tracked through UN and other demographic projections. This gap matters sociologically: policy is still being made against a population picture that is over a decade old.

The Long-Run Trajectory of India’s Population Growth

• India’s population growth since the start of the twentieth century did not rise steadily — it moved through distinct phases, each shaped by a different balance of birth and death rates, and this phased pattern is the backbone of any account of Indian population growth.
  • Phase of stagnant or slow growth (up to 1921). Between 1901 and 1921, both birth and death rates were high, so net growth stayed low, and 1911-1921 actually recorded a negative growth rate of -0.03% — the only decade in the twentieth century where India’s population fell. This was driven by the catastrophic influenza epidemic of 1918-19, which killed roughly 12.5 million people, about 5% of India’s population at the time, a toll documented by demographers Visaria and Visaria. Plague, malaria, and recurring famine compounded the high mortality of this phase.
  • Phase of steady increase (1921-1951). From 1921, death rates began a slow, steady decline as famine and epidemic control improved, while birth rates stayed high — the classic opening of a demographic transition. Growth remained modest, not exceeding an average annual rate of 1.33% across 1901-1951 as a whole.
  • Phase of rapid growth (1951 onward). After independence, public health measures curbed epidemics and famine deaths sharply, so death rates fell faster than birth rates could adjust. Growth accelerated to 2.2% annually during 1961-1981, and India’s population had nearly tripled since 1951 by the end of the twentieth century. Growth was consistently higher in the northern states than in the south, foreshadowing the regional fertility divide discussed below.
• The scale of this growth is easier to grasp in comparative terms: between 1971 and 2001 alone, India’s population rose from 548 million to 1029 million — an increase equivalent to two and a half times the population of the entire African continent, with a single decade’s growth roughly equal to the combined population of Canada and the United States. Every year, the addition to India’s population was comparable to the entire population of a country like Malaysia or Australia.
• The 2001-2011 decade marked a turning point: the decadal growth rate registered its sharpest decline since independence, falling by 3.90 percentage points, from 21.54% (1991-2001) to 17.64% (2001-2011) — the clearest sign that India had entered the later, slowing stage of its demographic transition even before total fertility reached replacement level nationally (discussed in the next article in this series).

Size, Density, and Distribution: The 2011 Census Picture

• According to the Census of 2011, India’s population stood at 121 crore (1.21 billion) — roughly 17.5% of the world’s population living on just 2.4% of the world’s land area, meaning that out of every 100 people on earth, about 15 were Indian.
• Density of population — persons per square kilometre — has risen steadily through every census: from 72 in 1901, to 267 in 1991, to 325 in 2001, to 382 in 2011.
  • Density is highly uneven across states. Arunachal Pradesh has consistently recorded the lowest density, followed by Mizoram, reflecting its mountainous terrain and low urbanisation.
  • At the other end, Bihar overtook West Bengal to become India’s most densely populated major state by the 2011 Census (a reversal of the 2001 ranking, when West Bengal led) — a shift worth noting explicitly, since older notes on this topic often still cite the 2001 ordering.
• Rural-urban distribution has shifted only gradually but consistently toward urban areas. Census figures show 25.7% of the population living in urban areas in 1991, rising to 27.8% in 2001, and 31.2% by the 2011 Census — a steady climb from around 11% urban at the start of the twentieth century, an increase of roughly two-and-a-half times over the century. Over 60% of the urban population is concentrated in agglomerations and cities with a population of one lakh or more, and this urban growth has been driven substantially by rural-to-urban migration in search of jobs, amenities, and a higher standard of living.
  • This urban share may itself be an undercount. The Economic Survey 2025-26 has argued that India may already be considerably more urban than the official ~31% figure suggests, given how much economic and infrastructural activity now clusters around urban and peri-urban corridors that census definitions of “urban” do not fully capture — a live methodological debate that the delayed Census 2021/2027 has made harder to resolve with fresh data.
• Religious composition (2011 Census): Hindus account for 79.8% of the population, Muslims for 14.2%, with Christians the third-largest group nationally, Sikhs concentrated heavily in Punjab, and Jains and Buddhists showing social patterns broadly similar to Hindus in most demographic respects. The Census also records detail on age, sex, marital status, literacy, and occupation, making it the single richest data source for the composition variables discussed below.

Age and Sex Composition: The Shape of the Population

• The age structure of a population — the proportion of people in each age band — is one of the most consequential composition variables, because it determines the dependency ratio: the number of dependents (children and the elderly) that each person of working age must support.
  • As of the 2001 Census, close to 40% of India’s population was below 15 years of age, with only 5-6% aged 60 and above, meaning nearly half the population was economically dependent on those in the earning age bracket. A large dependent share depresses savings and investment, since a greater share of household income is consumed rather than saved — a structural constraint on capital formation that recurs through India’s development history.
  • This youthful skew is also the source of India’s much-discussed “demographic dividend” — the economic boost that follows when the working-age share of the population rises relative to dependents, provided that this larger workforce is actually educated and employed. The dividend is not automatic: it requires deliberate policy investment in education and employment generation to be converted into actual growth, and it is temporary, since the same large working-age cohort eventually ages into a large elderly cohort itself (a dynamic examined in detail in the “Emerging Issues” article in this series).
  • The sex composition of India’s population has historically shown fewer females than males — a pattern this series examines in depth separately, since the sex ratio is treated as a distinct “emerging issue” in the syllabus given how sharply it has deteriorated at the child level even as the overall ratio has fluctuated.
• Compared to most other large economies, India’s age structure remains comparatively young, though this advantage is narrowing: the average Indian was projected to be about 29 years old in 2020, against an average age of 37 in China and the United States, 45 in Western Europe, and 48 in Japan. This gap is precisely what underpins arguments that India has a limited-duration window to exploit its demographic dividend before its own population begins ageing at scale.

The Postponed Census and India’s Current Population Picture

• India’s most consequential recent demographic fact is not found in the 2011 Census at all: by 2023, UN Department of Economic and Social Affairs estimates indicated that India had overtaken China to become the world’s most populous country, a milestone reached without any domestic census confirming it, since India’s own count had by then already been delayed for over a decade.
• The 2021 Census was postponed first due to the COVID-19 pandemic and then repeatedly due to administrative delay, making the gap between India’s two most recent censuses 16 years — unprecedented since independence. As of 2026, the Census exercise is finally under way in two phases: a House Listing and Housing Census from April to September 2026, followed by the Population Enumeration phase in February 2027. Until this new count is completed and published, most composition data cited in Indian sociology continues to rely on 2011 figures, even as India’s total population is separately estimated (by the UN and other agencies) at roughly 1.47 billion as of 2026.
• This prolonged data gap has real analytical consequences: policymakers and researchers have had to rely on proxy data sources — the NFHS, the SRS, and even non-traditional indicators like railway ticket bookings, banking transaction data, and telecom mobility data — to track internal migration and demographic change in the absence of an updated headcount, a workaround the Economic Advisory Council to the Prime Minister has itself proposed given the scale of the data gap.