What reputable sources actually say:
Population premise (UN, latest):
- China’s population in 2100 (UN WPP 2024, medium variant): ~633 million** (i.e., well over a 50% decline from ~1.43B).
- India’s population in 2100 (UN WPP 2024, medium variant): ~1.505 billion.** Peak ~1.7B in the early-2060s, then a gradual decline.
Projections on economic size (GDP):
- Goldman Sachs (2075):
“India will have the world’s second-largest economy by 2075.” (Nominal GDP; GS emphasizes demographics + productivity as the drivers.) - PwC — World in 2050 (PPP basis):
“China and India could be the two largest economies in the world by 2050,” with India #2 behind China in PPP terms. - CEBR (World Economic League Table – long horizon blog note):
“By 2100, India emerges as the biggest economic superpower, with GDP 90% larger than China’s and 30% larger than the US’s.” (Long-range scenario building on demographic dynamics.).
Implication: This is one of the few published, numerically explicit claims that India surpasses China by 2100. - OECD long-term scenarios (to 2060):
Show India’s growth contribution surpassing China’s by the mid-2030s, but they don’t project levels to 2100 or claim India overtakes China in aggregate GDP within their horizon. - IIASA/SSP academic scenario sets (to 2100):
Provide country-level GDP scenarios (not single forecasts) to 2100 used by the IPCC/NGFS community; they explicitly study whether India’s demographic edge plus human-capital gains could translate into relative economic leadership late-century.
CEBR — World Economic League Table (WELT)
CEBR’s 2023–24 long-horizon note says: “India emerges as the third and eventually the biggest economic superpower, with GDP by 2100 90% larger than China’s and 30% larger than the US’s.” The same page also states the US ends up ~45% larger than China by 2100.
How CEBR gets there (method sketch).
- Annual update using market-exchange-rate (nominal USD) GDP paths, not PPP.
- Medium-term (to ~2035) driven by consensus forecasts and house views; long-term driven by demographics, capital deepening and productivity assumptions by country/region.
CEBR (Centre for Economics and Business Research), a London-based independent economics consultancy (founded 1992). It publishes the annual World Economic League Table (WELT) projecting GDP sizes and ranks.
OECD — long-term scenarios to 2060
What the OECD says.
The OECD’s conditional-convergence model shows India’s contribution to global growth surpassing China’s in the mid/late-2030s (some editions say early-2040s).
- 2018 “Long View”: “By the mid-2030s, India’s growth contribution surpasses China’s.”
- 2021 “The long game”: India’s contribution surpasses China’s in the early-2040s in that update.
- 2023 energy-transition scenarios: “India’s contribution surpassing China’s in the late-2030s.”
How the OECD models the future.
- A global, country-level growth model with conditional convergence: TFP, demographics (working-age population/ageing), capital deepening, participation/education, and policy variables feed the baseline and alternative pathways. (Method detail in the reports.)
IIASA / SSP — scenario datasets to 2100 (used by IPCC & NGFS)
What they provide.
- The SSP Database gives country-level GDP (both PPP and, via conversion, MER/nominal) every five years to 2100 under five archetypal pathways (SSP1–SSP5), with variants across modelling teams.
- It’s a data platform, not a single forecast. Researchers (and central banks) use it to test “what-ifs” (education, fertility, participation, tech, policy).
How to read it for India vs China.
- Depending on the SSP and the labour-productivity and human-capital assumptions, several paths show India approaching or overtaking China late-century.
IIASA (the International Institute for Applied Systems Analysis), an independent research institute based in Laxenburg (near Vienna), Austria.
SSP — Shared Socioeconomic Pathways — a set of five globally consistent “what-if” storylines plus quantified datasets to 2100 (population, GDP, education, etc.).