Dependency ratios:
total dependency ratio: 74.2
[see also: Dependency ratios - total dependency ratio country ranks ]
youth dependency ratio: 63.9
[see also: Dependency ratios - youth dependency ratio country ranks ]
elderly dependency ratio: 10.2
[see also: Dependency ratios - elderly dependency ratio country ranks ]
potential support ratio: 9.8 (2015 est.)
[see also: Dependency ratios - potential support ratio country ranks ]

Median age:
total: 23 years
[see also: Median age - total country ranks ]
male: 22.5 years
[see also: Median age - male country ranks ]
female: 23.4 years (2017 est.)
[see also: Median age - female country ranks ]
country comparison to the world: 171

Population growth rate:
-0.05% (2017 est.)
country comparison to the world: 202
[see also: Population growth rate country ranks ]

Birth rate:
22.2 births/1,000 population (2017 est.)
country comparison to the world: 70
[see also: Birth rate country ranks ]

Death rate:
4.9 deaths/1,000 population (2017 est.)
country comparison to the world: 196
[see also: Death rate country ranks ]

Net migration rate:
-17.8 migrant(s)/1,000 population (2017 est.)
country comparison to the world: 218
[see also: Net migration rate country ranks ]

Population distribution:
over two-thirds of the population lives on the island of Tongatapu; only 45 of the nation's 171 islands are occupied

Urbanization:
urban population: 23.9% of total population (2017)
[see also: Urbanization - urban population country ranks ]
rate of urbanization: 1.3% annual rate of change (2015-20 est.)
[see also: Urbanization - rate of urbanization country ranks ]

Major urban areas - population:
NUKU'ALOFA 25,000 (2014)

Sex ratio:
at birth: 1.03 male(s)/female
[see also: Sex ratio - at birth country ranks ]
0-14 years: 1.03 male(s)/female
[see also: Sex ratio - 0-14 years country ranks ]
15-24 years: 1.05 male(s)/female
[see also: Sex ratio - 15-24 years country ranks ]
25-54 years: 1 male(s)/female
[see also: Sex ratio - 25-54 years country ranks ]
55-64 years: 0.98 male(s)/female
[see also: Sex ratio - 55-64 years country ranks ]
65 years and over: 0.84 male(s)/female
[see also: Sex ratio - 65 years and over country ranks ]
total population: 1.01 male(s)/female (2017 est.)
[see also: Sex ratio - total population country ranks ]

Mother's mean age at first birth:
24.9 years
note: median age at first birth among women 25-49 (2012 est.)

Maternal mortality ratio:
124 deaths/100,000 live births (2015 est.)
country comparison to the world: 68
[see also: Maternal mortality ratio country ranks ]

Infant mortality rate:
total: 11.3 deaths/1,000 live births
[see also: Infant mortality rate - total country ranks ]
male: 11.7 deaths/1,000 live births
[see also: Infant mortality rate - male country ranks ]
female: 10.8 deaths/1,000 live births (2017 est.)
[see also: Infant mortality rate - female country ranks ]
country comparison to the world: 126

Life expectancy at birth:
total population: 76.4 years
[see also: Life expectancy at birth - total population country ranks ]
male: 74.9 years
[see also: Life expectancy at birth - male country ranks ]
female: 78.1 years (2017 est.)
[see also: Life expectancy at birth - female country ranks ]
country comparison to the world: 87
[See also: Healthy Life Expectancy ]
[See also: Health Performance ]

Total fertility rate:
3.1 children born/woman (2017 est.)
country comparison to the world: 51
[see also: Total fertility rate country ranks ]

Contraceptive prevalence rate:
34.1% (2012)
[see also: Contraceptive prevalence rate country ranks ]

Health expenditures:
5.2% of GDP (2014)
country comparison to the world: 133
[see also: Health expenditures country ranks ]

Physicians density:
0.56 physicians/1,000 population (2010)
[see also: Physicians density country ranks ]

Hospital bed density:
2.6 beds/1,000 population (2010)
[see also: Hospital bed density country ranks ]

Drinking water source:
improved: urban: 99.7% of population rural: 99.6% of population total: 99.6% of population
unimproved: urban: 0.3% of population rural: 0.4% of population total: 0.4% of population (2015 est.)

Sanitation facility access:
improved: urban: 97.6% of population rural: 89% of population total: 91% of population
unimproved: urban: 2.4% of population rural: 11% of population total: 9% of population (2015 est.)

HIV/AIDS - adult prevalence rate:
NA
[see also: HIV/AIDS - adult prevalence rate country ranks ]

HIV/AIDS - people living with HIV/AIDS:
NA
[see also: HIV/AIDS - people living with HIV/AIDS country ranks ]

HIV/AIDS - deaths:
NA
[see also: HIV/AIDS - deaths country ranks ]

Major infectious diseases:
note: active local transmission of Zika virus by Aedes species mosquitoes has been identified in this country (as of August 2016); it poses an important risk (a large number of cases possible) among US citizens if bitten by an infective mosquito; other less common ways to get Zika are through sex, via blood transfusion, or during pregnancy, in which the pregnant woman passes Zika virus to her fetus (2016)

Obesity - adult prevalence rate:
48.2% (2016)
country comparison to the world: 7
[see also: Obesity - adult prevalence rate country ranks ]

Children under the age of 5 years underweight:
1.9% (2012)
[see also: Children under the age of 5 years underweight country ranks ]

Literacy:
definition: can read and write Tongan and/or English
total population: 99.4%
[see also: Literacy - total population country ranks ]
male: 99.3%
[see also: Literacy - male country ranks ]
female: 99.4% (2015 est.)