A lunar calendar is a calendar that is based on cycles of the lunar phase. A common purely lunar calendar is the Islamic calendar or Hijri Qamari calendar. A feature of the Islamic calendar is that a year is always 12 months, so the months are not linked with the seasons and drift each solar year by 11 to 12 days. It comes back to the position it had in relation to the solar year approximately every 33 Islamic years. It is used mainly for religious purposes, and in Saudi Arabia it is also used for commercial purposes. Because there are about twelve lunations (synodic months) in a solar year, this period (354.37 days) is sometimes referred to as a lunar year. The Hebrew calendar also uses a fixed ratio (12+7/19) so it will eventually drift, such that Passover would be in autumn.

Ein Lunarkalender oder Mondkalender ist ein am Lauf des Mondes orientierter Kalender. Zur Abgrenzung gegen einen Lunisolarkalender werden auch die Bezeichnungen freier Lunarkalender oder ungebundener Lunarkalender verwendet.

Un calendrier lunaire est un calendrier réglé sur les phases de la Lune. Un mois, dans un tel calendrier, représente une lunaison.

Månkalender, kalender som bygger på månens faser. De första som använde en kalender var babylonierna för cirka 5000 år sedan. De mätte upp ett år genom att observera månens faser. Den idag mest spridda rena månkalendern är den muslimska.

Um calendário lunar é um calendário cuja data indica a fase da lua.