This is a list of sovereign states by the date in which they adopted their current national flag.
For most countries, the date of flag adoption is obvious, but for others it is more debatable. The exact date or year of flag adoption can be unknown or disputed because of design changes. This list defines the moment of flag adoption as the year since when the current flag had a continuous use to represent a nation, autonomous region or occupied state. Only countries that currently form a sovereign state are listed although the flag can be adopted before the countries gained independence. The listed countries may have gone through fundamental regime changes, big geographical changes or even temporary lost autonomy, joint bigger unions or split up. If the flag remained in use during such a period the original adoption date is used. Changes that do not alter the basic design of the flag; like the changes in ratio or colour shade, restyling of emblems or inscriptions or the addition or removal of stars, are listed in the last column. The current flag design often evolved over the years (e.g. the flag of the United States) or can be a re-adoption of an earlier, historic flag (e.g. the flag of Libya). The year the current flag design first came into use is listed in the middle column.