| a | | Including Ascension and Tristan da Cunha. For statistical purposes, the data for United Kingdom do not include this area. |
| b | | Projected est. (medium fertility variant). |
| c | | Including Ascension and Tristan da Cunha. |
| d | | St. Helena Island has no substantial natural inland waters however there are 15 reservoirs and similar open water storage features on island. |
| e | | 2023 |
| f | | 2018 |
| g | | 2024 |
| h | | Estimate. |
| i | | 2021 |
| j | | 2019 |
| k | | Data refers to a 5-year period preceding the reference year. |
| l | | Calculated by the UN Statistics Division. |
| m | | Refers to foreign citizens. |
| n | | For statistical purposes, the foreign-born population includes persons born in United Kingdom, Anguilla, Bermuda, British Virgin Islands, Cayman Islands, Channel Islands, Falkland Islands (Malvinas), Gibraltar, Isle of Man, Montserrat, and Turks and Caicos Islands. |
| o | | 2012 |
| p | | 2022 |