The population on 1 January 2011 was 318,452 compared with 317,630 in 2010. This constitutes an increase of 0.3%. The population declined in five regions, mostly in the Westfjords which lost 3.1% of its population in 2010. Three regions experienced a population increase. The capital region gained the most where the population increased by 1,434 persons, or 0.7%.
The number of municipalities by 1 January 2011 was 76, down by one in 2010 due to the merging of two small municipalities in the Northeast region. Five municipalities have fewer than 100 inhabitants, and 43 have fewer than 1,000 inhabitants.
The dependency ratio was 68.1% on 1 January 2011, a slight increase from previous year when it was 67.8%. The dependency ratio is calculated as the ratio of the young and old to the working age population of 20–64 years of age.
The number of nuclear families, i.e. couples with or without children under 18 years or parents with children under 18 years, was 77,370 on 1 January 2011, compared with 77,227 families in 2010.
| Population by regions 1 January 2010 and 2011 | |||||
| Increse/decrease | |||||
| from previous | Percentage distribution | ||||
| 2010 | 2011 | year (%) | 2010 | 2011 | |
| Total | 317,630 | 318,452 | 0.3 | 100.0 | 100.0 |
| Capital region | 200,907 | 202,341 | 0.7 | 63.3 | 63.5 |
| Southwest | 21,359 | 21,088 | -1.3 | 6.7 | 6.6 |
| West | 15,370 | 15,379 | 0.1 | 4.8 | 4.8 |
| Westfjords | 7,362 | 7,137 | -3.1 | 2.3 | 2.2 |
| Northwest | 7,394 | 7,393 | 0.0 | 2.3 | 2.3 |
| Northeast | 28,900 | 29,006 | 0.4 | 9.1 | 9.1 |
| East | 12,459 | 12,306 | -1.2 | 3.9 | 3.9 |
| South | 23,879 | 23,802 | -0.3 | 7.5 | 7.5 |
The population development in 2010 will be further analysed in the Statistical Series, due to be published 29 March this year.