Population: Total population and distribution by age and sex estimated to be consistent with the population by age and sex of the (a) 1961, 1971, 1981, 1991, 2001, 2011 censuses; (b) adjusted for under/over count; (c) adjusted for age heaping; (d) adjusted for under enumeration of children under age 15; (e) 1992-1993 NFHS survey estimates; and with estimates of the subsequent trends in fertility, mortality and international migration.  In addition, the official estimates through 2021 have been considered.
Note: 1981 census adjusted to include Assam, and 1991 census adjusted to include Jammu and Kashmir.

Fertility: Total fertility rate and age pattern of fertility based on: (a) registered births classified by age of mother and the underlying female population by age through 2019; (b) birth-histories data from the 1992-1993, 1998-1999, 2005-2006, 2015-2016 NFHS; (c) births in the household in the preceding 12 (or 24) months classified by age of mother from the 1969-2019 SRS and 2007-2008 DLHS and 2019-2021 NFHS-5; (d) adjusted fertility using synthetic relational Gompertz model with data on children ever born and births in the preceding 12 (or 24/36) months, both classified by age of mother, from the 1979 SICM and 1981, 1991, 2001 censuses; (e) indirect estimates based on the increment of cohort parities between successive censuses or surveys such as the 1951, 1961, 1971, 1981, 1991 censuses; (f) indirect estimates obtained from the application of the reverse survival method to the 1961, 1971, 1981, 1991, 2001, 2011 censuses; (g) cohort-completed fertility backdated by the mean age of childbearing from the 1970-1971 NFPS and 1979 SICM and 1981 Census and 1992-1993, 1998-1999, 2005-2006, 2015-2016 NFHS.  In addition, the (a) official estimates of age-specific fertility rates through 2017; (b) births in the household in the preceding 12 (or 24) months classified by age of mother from the 1979 SICM and 1981, 1991, 2001, 2011 censuses; (c) indirect estimates obtained from the application of the reverse survival method to the 1951 Census and 1957-2011 Education Stats; (d) indirect estimates obtained from the application of the own-children method of fertility estimation to the 2002-2004, 2007-2008 DLHS; (e) cohort-completed fertility backdated by the mean age of childbearing from the 1991, 2001, 2011 censuses have been considered.

Child Mortality: Under-five mortality based on: (a) official estimates of infant and child mortality through 2017; (b) registered infant and child deaths through 2018; (c) direct estimates from births and deaths under-five calculated from full birth histories data from the 1992-1993, 1998-1999, 2005-2006 NFHS; (d) indirect estimates from data on children ever born and surviving from the 1965-1966 NSS and 1970-1971 NFPS and 1972 FS and 1980-1981 FPS and 1998-1999, 2002-2004, 2007-2008 DLHS and 2011 Census; (e) recent household deaths from the 1945-2020 SRS; (f) International estimates used up to 2021.  In addition, the (a) direct estimates from births and deaths under-five calculated from full birth histories data from the 2015-2016 NFHS and 2019-2020 DHS; (b) indirect estimates from data on children ever born and surviving from the 1981, 1991, 2001 censuses; (c) recent household deaths from the 1971 Census and 1992-1993, 1998-1999 NFHS have been considered.

Overall Mortality: Life expectancy at birth and age pattern of mortality based on: (a) official estimates through 2017; (b) registered deaths by age and sex available through 2018; (c) adjusted for underreporting of infant and child deaths; (d) adult deaths adjusted for underregistration using death distribution methods; (e) mortality rates for older ages were adjusted; (f) estimates using CD West model life tables and estimates of under-five mortality (5q0), and adult mortality (45q15).  In addition, the (a) registered deaths by age and sex available through 2018; (b) adjusted for underreporting of infant and child deaths; (c) adult deaths adjusted for underregistration using death distribution methods; (d) mortality rates for older ages were adjusted have been considered.

Adult and Old Age Mortality: Estimates derived from: (a) recent household deaths data by age and sex from the 1970-2018 SRS and 1971 Census and 1992-1993, 1998-1999, 2015-2016 NFHS and 2012-2014 DLHS; (b) recent household deaths adjusted at adult ages for underregistration using death distribution methods; (c) intercensal survivorship from successive census age distributions; (d) estimates of under-five, adult and old age mortality.  In addition, the (a) recent household deaths data by age and sex from the 1950-2018 Register; (b) recent household deaths adjusted at adult ages for underregistration using death distribution methods; (c) intercensal survivorship from successive census age distributions have been considered.

Migration: International migration based on: (a) information on foreign-born populations from censuses and registers from major countries of destination; (b) information on the number of migrant workers or about labor migration; (c) estimates derived as the differences between overall population growth and natural increase; (d) UNHCR statistics on the number of refugees in the main countries of asylum.