Liturgical Calendar for 2021
Welcome. Here, you will find a traditional Catholic calendar containing all the feasts for the current liturgical year. Note that Sundays are marked with bold letters, and each tab provides sorting and searching functionality.
If you would to see the liturgical calendar for 2020, please click here
2 The Ashmolean Latin Inscriptions Project B. Days Instead of describing the date as 1st, 2nd, 3rd, 4th and so on, the Romans used a very different system. There were three special days in every month: - The Kalends: the first day of the month, when the moon was thin crescent. The place to find Latin Dancing Classes, Events, Festivals, Workshops & more. Come join the thousands of people already using Latin Dance Calendar. Catholic Calendar for the Tradtional Latin Liturgy. Sunday: Monday: Tuesday: Wednesday: Thursday: Friday: Saturday.
Date | Feast | Class |
---|---|---|
1 | Octave Day of Christmas | 1st class |
2 | Saturday of Our Lady or Immaculate Heart of Mary | 4th class 3rd class |
3 | Most Holy Name of Jesus | 2nd class |
4 | Feria of Christmastide or (USA) St. Elizabeth Ann Seton | 4th class 3rd class |
5 | Feria of Christmastide or St. Telesphorus or (USA) St. John Neumann | 4th class 4th class 3rd class |
6 | Epiphany of the Lord | 1st class |
7 | Feria after the Epiphany or Jesus Christ the High Priest | 4th class 3rd class |
8 | Feria after the Epiphany | 4th class |
9 | Saturday of Our Lady | 4th class |
10 | The Holy Family | 2nd class |
11 | Feria after the Epiphany or St. Hyginus | 4th class 4th class |
12 | Feria after the Epiphany | 4th class |
13 | Commemoration of Baptism of Our Lord | 2nd class |
14 | St. Hilary | 3rd class |
15 | St. Paul, the First Hermit | 3rd class |
16 | St. Marcellus I | 3rd class |
17 | 2nd Sunday after Epiphany | 2nd class |
18 | Feria St. Prisca or Votive Mass of the Chair of St. Peter | 4th class 4th class 4th class |
19 | Feria or Sts. Marius, Martha, Audifax & Abachum or St. Canute | 4th class 4th class 4th class |
20 | Sts. Fabian & Sebastian | 3rd class |
21 | St. Agnes | 3rd class |
22 | Sts. Vincent & Anastasius or (USA) Votive Mass for Peace | 3rd class 2nd class |
23 | St. Raymond of Penafort | 3rd class |
24 | 3rd Sunday after Epiphany | 2nd class |
25 | Conversion of St. Paul | 3rd class |
26 | St. Polycarp | 3rd class |
27 | St. John Chrysostom | 3rd class |
28 | St. Peter Nolasco | 3rd class |
29 | St. Francis de Sales | 3rd class |
30 | St. Martina | 3rd class |
31 | Septuagesima Sunday | 2nd class |
Date | Feast | Class |
---|---|---|
1 | St. Ignatius of Antioch or Immaculate Heart of Mary | 3rd class 3rd class |
2 | Purification of the Blessed Virgin Mary | 2nd class |
3 | Feria or St. Blaise | 4th class 4th class |
4 | St. Andrew Corsini or Jesus Christ the High Priest | 3rd class 3rd class |
5 | St. Agatha or Sacred Heart of Jesus | 3rd class 3rd class |
6 | St. Titus or Immaculate Heart of Mary | 3rd class 3rd class |
7 | Sexagesima Sunday | 2nd class |
8 | St. John of Matha | 3rd class |
9 | St. Cyril of Alexandria | 3rd class |
10 | St. Scholastica | 3rd class |
11 | Our Lady of Lourdes | 3rd class |
12 | Seven Holy Servite Founders | 3rd class |
13 | Saturday of Our Lady | 4th class |
14 | Quinquagesima Sunday | 2nd class |
15 | Feria or Sts. Faustinus & Jovita | 4th class 4th class |
16 | Feria | 4th class |
17 | Ash Wednesday | 1st class |
18 | Thursday after Ash Wednesday | 3rd class |
19 | Friday after Ash Wednesday | 3rd class |
20 | Saturday after Ash Wednesday | 3rd class |
21 | 1st Sunday of Lent | 1st class |
22 | Chair of St. Peter or (FSSP) Chair of St. Peter | 2nd class 1st class |
23 | Feria of Lent | 3rd class |
24 | St. Matthias | 2nd class |
25 | Feria of Lent | 3rd class |
26 | Ember Friday in Lent | 2nd class |
27 | Ember Saturday in Lent | 2nd class |
28 | 2nd Sunday of Lent | 1st class |
Date | Feast | Class |
---|---|---|
1 | Feria of Lent | 3rd class |
2 | Feria of Lent | 3rd class |
3 | Feria of Lent | 3rd class |
4 | Feria of Lent | 3rd class |
5 | Feria of Lent | 3rd class |
6 | Feria of Lent | 3rd class |
7 | 3rd Sunday of Lent | 1st class |
8 | Feria of Lent | 3rd class |
9 | Feria of Lent | 3rd class |
10 | Feria of Lent | 3rd class |
11 | Feria of Lent | 3rd class |
12 | Feria of Lent | 3rd class |
13 | Feria of Lent | 3rd class |
14 | 4th Sunday of Lent (Laetare Sunday) | 1st class |
15 | Feria of Lent | 3rd class |
16 | Feria of Lent | 3rd class |
17 | Feria of Lent | 3rd class |
18 | Feria of Lent | 3rd class |
19 | St. Joseph, Spouse of the Bl. Virgin Mary | 1st class |
20 | Feria of Lent (Sitientes) or Votive Mass (Anniversary of Coronation of Pope) (transferred) | 3rd class 2nd class |
21 | Passion Sunday | 1st class |
22 | Monday of Passion Week | 3rd class |
23 | Tuesday of Passion Week | 3rd class |
24 | Wednesday of Passion Week | 3rd class |
25 | Annunciation of the Blessed Virgin Mary | 1st class |
26 | Friday of Passion Week | 3rd class |
27 | Saturday of Passion Week | 3rd class |
28 | Palm Sunday | 1st class |
29 | Monday of Holy Week | 1st class |
30 | Tuesday of Holy Week | 1st class |
31 | Wednesday of Holy Week | 1st class |
Date | Feast | Class |
---|---|---|
1 | Holy Thursday | 1st class |
2 | Good Friday | 1st class |
3 | Holy Saturday and Easter Vigil | 1st class |
4 | Easter Sunday | 1st class |
5 | Easter Monday | 1st class |
6 | Easter Tuesday | 1st class |
7 | Easter Wednesday | 1st class |
8 | Easter Thursday | 1st class |
9 | Easter Friday | 1st class |
10 | Easter Saturday | 1st class |
11 | Low Sunday (Divine Mercy Sunday) | 1st class |
12 | Feria in Paschaltide | 4th class |
13 | St. Hermenegild | 3rd class |
14 | St. Justin | 3rd class |
15 | Feria in Paschaltide | 4th class |
16 | Feria in Paschaltide | 4th class |
17 | Saturday of Our Lady or St. Anicetus | 4th class 4th class |
18 | 2nd Sunday after Easter (Good Shepherd Sunday) | 2nd class |
19 | Feria in Paschaltide | 4th class |
20 | Feria in Paschaltide | 4th class |
21 | St. Anselm | 3rd class |
22 | Sts. Soter & Caius | 3rd class |
23 | Feria in Paschaltide or St. George | 4th class 4th class |
24 | St. Fidelis of Sigmaringen | 3rd class |
25 | 3rd Sunday after Easter or Rogation Mass | 2nd class 2nd class |
26 | Sts. Cletus & Marcellinus | 3rd class |
27 | St. Peter Canisius | 3rd class |
28 | St. Paul of the Cross | 3rd class |
29 | St. Peter of Verona | 3rd class |
30 | St. Catherine of Siena | 3rd class |
Date | Feast | Class |
---|---|---|
1 | St. Joseph the Workman | 1st class |
2 | 4th Sunday after Easter | 2nd class |
3 | Feria or Sts. Alexander & Companions or Finding of the Holy Cross | 4th class 4th class 4th class |
4 | St. Monica | 3rd class |
5 | St. Pius V | 3rd class |
6 | Feria of Paschaltide or St. John Before the Latin Gate or Jesus Christ the High Priest | 4th class 4th class 4th class |
7 | St. Stanislaus or Sacred Heart of Jesus | 3rd class 3rd class |
8 | Saturday of Our Lady or Apparition of St. Michael or Our Lady Mediatrix of All Graces | 4th class 4th class 4th class |
9 | 5th Sunday after Easter | 2nd class |
10 | St. Antoninus or Rogation Mass | 3rd class 2nd class |
11 | Sts. Philip & James or Rogation Mass | 2nd class 2nd class |
12 | Vigil of the Ascension or Rogation Mass | 2nd class 2nd class |
13 | Ascension of the Lord | 1st class |
14 | Feria after Ascension or St. Boniface | 4th class 4th class |
15 | St. John Baptist de la Salle | 3rd class |
16 | Sunday after Ascension | 2nd class |
17 | St. Paschal Baylon | 3rd class |
18 | St. Venantius | 3rd class |
19 | St. Peter Celestine | 3rd class |
20 | St. Bernardine of Siena | 3rd class |
21 | Feria after Ascension | Feria after Ascension |
22 | Vigil or Pentecost (until Mass exclusive) | 1st class |
23 | Pentecost Sunday | 1st class |
24 | Monday after Pentecost | 1st class |
25 | Tuesday after Pentecost | 1st class |
26 | Ember Wednesday of Pentecost | 1st class |
27 | Thursday after Pentecost | 1st class |
28 | Ember Friday of Pentecost | 1st class |
29 | Ember Saturday of Pentecost | 1st class |
30 | Trinity Sunday | 1st class |
31 | Queenship of Mary | 2nd class |
Date | Feast | Class |
---|---|---|
1 | St. Angela Merici | 3rd class |
2 | Feria (Mass of 1st Sunday after Pentecost) or Sts. Marcellinus, Peter, & Erasmus | 4th class 4th class |
3 | Corpus Christi | 1st class |
4 | St. Francis Caracciolo or Sacred Heart of Jesus | 3rd class 3rd class |
5 | St. Boniface or Immaculate Heart of Mary | 3rd class 3rd class |
6 | 2nd Sunday after Pentecost or (USA) External Solemnity of Corpus Christi | 2nd class 2nd class |
7 | Feria | 4th class |
8 | Feria | 4th class |
9 | Feria or Sts. Primus & Felicianus | 4th class 4th class |
10 | St. Margaret of Scotland | 3rd class |
11 | Sacred Heart of Jesus | 1st class |
12 | St. John of San Facundo | 3rd class |
13 | 3rd Sunday after Pentecost or External Solemnity of the Sacred Heart | 2nd class 2nd class |
14 | St. Basil the Great | 3rd class |
15 | Feria or Sts. Vitus, Modetus, & Crescentia | 4th class 4th class |
16 | Feria | 4th class |
17 | St. Gregory Barbarigo | 3rd class |
18 | St. Ephrem of Syria | 3rd class |
19 | St. Juliana of Falconieri | 3rd class |
20 | 4th Sunday after Pentecost | 2nd class |
21 | St. Aloysius Gongzaga | 3rd class |
22 | St. Paulinus of Nola | 3rd class |
23 | Vigil of the Nativity of St. John the Baptist | 2nd class |
24 | Nativity of St. John the Baptist | 1st class |
25 | St. William | 3rd class |
26 | Sts. John & Paul | 3rd class |
27 | 5th Sunday after Pentecost | 2nd class |
28 | Vigil of Sts. Peter & Paul | 2nd class |
29 | Sts. Peter & Paul | 1st class |
30 | Commemoration of St. Paul | 3rd class |
Date | Feast | Class |
---|---|---|
1 | The Precious Blood of Our Lord Jesus Christ | 1st class |
2 | Visitation of the Blessed Virgin Mary | 2nd class |
3 | St. Irenaeus or Immaculate Heart of Mary | 3rd class 3rd class |
4 | 6th Sunday after Pentecost or (USA) External Solemnity of Sts. Peter and Paul | 2nd class 2nd class |
5 | St. Anthony Mary Zaccariah | 3rd class |
6 | Feria | 4th class |
7 | Sts. Cyril & Methodius | 3rd class |
8 | St. Elizabeth of Portugal | 3rd class |
9 | Feria | 4th class |
10 | Seven Holy Brothers and Sts. Rufina & Secunda | 3rd class |
11 | 7th Sunday after Pentecost | 2nd class |
12 | St. John Gualbert | 3rd class |
13 | Feria | 4th class |
14 | St. Bonaventure | 3rd class |
15 | St. Henry the Emperor | 3rd class |
16 | Feria or Our Lady of Mt. Carmel | 4th class 4th class |
17 | Saturday of Our Lady or St. Alexis | 4th class 4th class |
18 | 8th Sunday after Pentecost | 2nd class |
19 | St. Vincent de Paul | 3rd class |
20 | St. Jerome Emiliani | 3rd class |
21 | St. Lawrence of Brindisi | 3rd class |
22 | St. Mary Magdalene | 3rd class |
23 | St. Apollinaris | 3rd class |
24 | Saturday of Our Lady or St. Christina | 4th class 4th class |
25 | 9th Sunday after Pentecost | 2nd class |
26 | St. Anne, Mother of the Blessed Virgin | 2nd class |
27 | Feria or St. Pantaleon | 4th class 4th class |
28 | Sts. Nazarius & Celsus, St. Victor 1, St. Innocent 1 | 3rd class |
29 | St. Martha | 3rd class |
30 | Feria or Sts. Abdon & Sennen | 4th class 4th class |
31 | St. Ignatius Loyola | 3rd class |
Date | Feast | Class |
---|---|---|
1 | 10th Sunday after Pentecost | 2nd class |
2 | St. Alphonsus Liguori | 3rd class |
3 | Feria or Finding of the Body of St. Stephen | 4th class 4th class |
4 | St. Dominic | 3rd class |
5 | Dedication of the Basilica of St. Mary Major or Jesus Christ the High Priest | 3rd class 3rd class |
6 | Transfiguration of Our Lord | 2nd class |
7 | St. Cajetan or Immaculate Heart of Mary | 3rd class 3rd class |
8 | 11th Sunday after Pentecost | 2nd class |
9 | Vigil of St. Lawrence | 3rd class |
10 | St. Lawrence | 2nd class |
11 | Feria or Sts. Tiburtius & Susanna | 4th class 4th class |
12 | St. Clare | 3rd class |
13 | Feria or Sts. Hippolytus & Cassian | 4th class 4th class |
14 | Vigil of the Assumption | 2nd class |
15 | Assumption of the Blessed Virgin Mary | 1st class |
16 | St. Joachim, Father of the Blessed Virgin | 2nd class |
17 | St. Hyacinth | 3rd class |
18 | Feria or St. Agapitus | 4th class 4th class |
19 | St. John Eudes | 3rd class |
20 | St. Bernard of Clairvaux | 3rd class |
21 | St. Jane Frances de Chantal | 3rd class |
22 | 13th Sunday after Pentecost | 2nd class |
23 | St. Philip Benizi | 3rd class |
24 | St. Bartholomew | 2nd class |
25 | St. Louis IX | 3rd class |
26 | Feria or St. Zephyrinus | 4th class 4th class |
27 | St. Joseph Calasanctius | 3rd class |
28 | St. Augustine | 3rd class |
29 | 14th Sunday after Pentecost | 2nd class |
30 | St. Rose of Lima | 3rd class |
31 | St. Raymond Nonnatus | 3rd class |
Date | Feast | Class |
---|---|---|
1 | Feria or St. Files or Twelve Holy Brothers | 4th class 4th class 4th class |
2 | St. Stephen of Hungary or Jesus the High Priest | 3rd class 3rd class |
3 | St. Pius X or Sacred Heart of Jesus | 3rd class 3rd class |
4 | Saturday of Our Lady or Immaculate Heart of Mary | 4th class 3rd class |
5 | 15th Sunday after Pentecost | 2nd class |
6 | Feria | 4th class |
7 | Feria | 4th class |
8 | Nativity of the Blessed Virgin Mary | 2nd class |
9 | Feria or St. Gorgonius or (USA) St. Peter Claver | 4th class 4th class 3rd class |
10 | St. Nicholas of Tolentino | 3rd class |
11 | Saturday of Our Lady or Sts. Protus & Hyacinth | 4th class 4th class |
12 | 16th Sunday after Pentecost | 2nd class |
13 | Feria | 4th class |
14 | Exaltation of the Holy Cross | 2nd class |
15 | Seven Sorrows of the Blessed Virgin Mary | 2nd class |
16 | Sts. Cornelius & Cyprian | 3rd class |
17 | Feria or Stigmata of St. Francis | 4th class 4th class |
18 | St. Joseph Cupertino | 3rd class |
19 | 17th Sunday after Pentecost | 2nd class |
20 | Feria (4th class) or Sts. Eustace & Companions | 4th class 4th class |
21 | St. Matthew | 2nd class |
22 | Ember Wednesday | 2nd class |
23 | St. Linus | 3rd class |
24 | Ember Friday | 2nd class |
25 | Ember Saturday | 2nd class |
26 | 18th Sunday after Pentecost | 2nd class |
27 | Sts. Cosmas & Damian | 3rd class |
28 | St. Wenceslaus | 3rd class |
29 | Dedication of St. Michael the Archangel | 1st class |
30 | St. Jerome | 3rd class |
Date | Feast | Class |
---|---|---|
1 | Feria or St. Remigius or Sacred Heart of Jesus | 4th class 4th class 3rd class |
2 | Holy Guardian Angels or Immaculate Heart of Mary | 3rd class 3rd class |
3 | 19th Sunday after Pentecost or External Solemnity of Our Lady of the Rosary | 2nd class 2nd class |
4 | St. Francis of Assisi | 3rd class |
5 | Feria or St. Placid & Companions | 4th class 4th class |
6 | St. Bruno | 3rd class |
7 | Our Lady of the Rosary | 2nd class |
8 | St. Bridget of Sweden | 3rd class |
9 | St. John Leonardi | 3rd class |
10 | 20th Sunday after Pentecost | 2nd class |
11 | Maternity of the Blessed Virgin Mary | 2nd class |
12 | Feria | 4th class |
13 | St. Edward the Confessor | 3rd class |
14 | St. Callistus I | 3rd class |
15 | St. Teresa of Avila | 3rd class |
16 | St. Hedwig or (Canada) St. Marguerite d'Youville | 3rd class 3rd class |
17 | 21st Sunday after Pentecost | 2nd class |
18 | St. Luke the Evangelist | 2nd class |
19 | St. Peter of Alcantara | 3rd class |
20 | St. John Cantius | 3rd class |
21 | Feria or St. Hilarion or Sts. Ursula & Companions | 4th class 4th class 4th class |
22 | Feria | 4th class |
23 | St. Anthony Mary Claret | 3rd class |
24 | 22nd Sunday after Pentecost | 2nd class |
25 | Feria or Sts. Chrysanthus & Daria | 4th class 4th class |
26 | Feria or St. Evaristus | 4th class 4th class |
27 | Feria | 4th class |
28 | Sts. Simon & Jude | 2nd class |
29 | Feria | 4th class |
30 | Saturday of Our Lady | 4th class |
31 | Christ the King | 1st class |
Date | Feast | Class |
---|---|---|
1 | All Saints | 1st class |
2 | Commemoration of All Souls | 1st class |
3 | Feria or Daily Mass for the Dead | 4th class 3rd class |
4 | St. Charles Borromeo or (Seminaries) St. Charles Borromeo or Daily Mass for the Dead or Jesus Christ the High Priest | 3rd class 1st class 3rd class 3rd class |
5 | Feria or Daily Mass for the Dead or The Holy Relics or (FSSP) Daily Mass for Dead (Deceased FSSP & Confraternity members) or Sacred Heart of Jesus | 4th class 3rd class 4th class 4th class 3rd class |
6 | Saturday of Our Lady or Daily Mass for the Dead or Immaculate Heart of Mary | 4th class 3rd class 3rd class |
7 | Resumed 5th Sunday after Epiphany | 2nd class |
8 | Feria or Daily Mass for the Dead or Four Holy Crowned Martyrs | 4th class 3rd class 4th class |
9 | Dedication of the Archbasilica of Our Holy Savior | 2nd class |
10 | St. Andrew Avellino | 3rd class |
11 | St. Martin of Tours | 3rd class |
12 | St. Martin I | 3rd class |
13 | St. Didacus or (USA) St. Frances Xavier Cabrini | 3rd class 3rd class |
14 | Resumed 6th Sunday after Epiphany | 2nd class |
15 | St. Albert the Great | 3rd class |
16 | St. Gertrude the Great | 3rd class |
17 | St. Gregory the Wonderworker | 3rd class |
18 | Dedication of the Basilicas of Sts. Peter & Paul | 3rd class |
19 | St. Elizabeth of Hungary | 3rd class |
20 | St. Felix of Valois | 3rd class |
21 | 24th Sunday after Pentecost | 2nd class |
22 | St. Cecilia | 3rd class |
23 | St. Clement I | 3rd class |
24 | St. John of the Cross | 3rd class |
25 | St. Catherine of Alexandria | 3rd class |
26 | St. Sylvester | 3rd class |
27 | Saturday of Our Lady or Our Lady of the Miraculous Medal | 4th class 4th class |
28 | First Sunday of Advent | 1st class |
29 | Feria of Advent | 3rd class |
30 | St. Andrew | 2nd class |
Catholic Traditional Latin Mass Calendar
Date | Feast | Class |
---|---|---|
1 | Feria of Advent | 3rd class |
2 | St. Bibiana or Jesus the High Priest | 3rd class 3rd class |
3 | St. Francis Xavier or (Missions) St. Francis Xavier or Sacred Heart of Jesus | 3rd class 1st class 3rd class |
4 | St. Peter Chrysologus or Immaculate Heart of Mary | 3rd class 3rd class |
5 | 2nd Sunday of Advent | 1st class |
6 | St. Nicholas | 3rd class |
7 | St. Ambrose | 3rd class |
8 | Immaculate Conception of the Blessed Virgin Mary | 1st class |
9 | Feria of Advent | 3rd class |
10 | Feria of Advent | 3rd class |
11 | St. Damasus I | 3rd class |
12 | 3rd Sunday of Advent (Gaudete Sunday) | 1st class |
13 | St. Lucy | 3rd class |
14 | Feria of Advent | 3rd class |
15 | Ember Wednesday of Advent | 2nd class |
16 | St. Eusebius | 3rd class |
17 | Ember Friday of Advent | 2nd class |
18 | Ember Saturday of Advent | 2nd class |
19 | 4th Sunday of Advent | 1st class |
20 | Greater Feria of Advent | 2nd class |
21 | St. Thomas | 2nd class |
22 | Greater Feria of Advent | 2nd class |
23 | Greater Feria of Advent | 2nd class |
24 | Vigil of Christmas | 1st class |
25 | The Nativity of Our Lord | 1st class |
26 | Sunday within the Octave of Christmas | 2nd class |
27 | St. John the Evangelist | 2nd class |
28 | Holy Innocents | 2nd class |
29 | 5th Day in the Octave of Christmas | 2nd class |
30 | 6th Day in the Octave of Christmas | 2nd class |
31 | 7th Day in the Octave of Christmas | 2nd class |
By Konstantin Bikos and Vigdis Hocken
The Roman calendar is the ancestor of our modern calendar. Some of its features are still in use today.
What Is the Roman Calendar?
The Roman calendar is the time reckoning system used in ancient Rome. However, because the calendar was reformed and adjusted countless times over the centuries, the term essentially denotes a series of evolving calendar systems, whose structures are partly unknown and vary quite a bit.
Here, we focus mainly on the calendar used in the Roman Republic (509-27 BCE). Also known as the Republican calendar, it is the earliest calendar system from Rome for which we have historical evidence. It was used until 45 BCE, when it was replaced by the Julian calendar.
Based on Ancient Lunar Calendars
The Republican calendar was derived from a line of older calendar systems whose exact design is largely unknown. It is believed that the original Roman calendar was a lunar calendar that followed the phases of the Moon. This basic structure was preserved through the centuries, which is the reason why we use months today.
Only 10 Months at First
According to tradition, Romulus, the legendary first king of Rome, oversaw an overhaul of the Roman calendar system around 738 BCE. The resulting calendar, whose structure borrowed heavily from the ancient Greek calendar system, had only 10 months, with March (Martius) being the first month of the year. The winter season was not assigned to any month, so the year only lasted 304 days, with 61 days unaccounted for in the winter.
Republican Calendar Adds January and February
Following another calendar reform, which later Roman writers attributed to Romulus' successor, Numa Pompilius, the Republican calendar was instituted. To account for the days of winter between the years, two additional months were introduced: Ianuarius and Februarius.
This meant that some of the month names no longer agreed with their position in the calendar. For example, September means “the 7th month,” but it was now the 9th month of the year—an inconsistency that was preserved and is still part of the Gregorian calendar we use today.
A common year was now divided into 12 months of different lengths: 4 “full” months with 31 days, 7 “hollow” months with 29 days, and 1 month with 28 days.
The Leap Month, Mercedonius
The Republican calendar year lasted for 355 days, which is about 10 days shorter than a tropical year, the time it takes Earth to revolve around the Sun. To keep the calendar in sync with the seasons, a leap month called Mercedonius or Intercalaris was added in some years—normally every two to three years.
By custom, the insertion of the leap month was initiated by the pontifex maximus, the high priest of the College of Pontiffs in ancient Rome. However, this system was vulnerable to abuse. Since the Roman calendar year defined the term of office of elected officials, a pontifex maximus was able to control the length of his term simply by adding a leap month.
Traditional Latin Calendar
When Julius Caesar became pontifex maximus, he ordered a calendar reform which eliminated leap months and resulted in the implementation of the Julian calendar in 45 BCE, the direct predecessor of today's Gregorian calendar.
Calends, Nones, and Ides
The Roman calendar highlighted a number of days in each month:
Washington Latin Calendar
- Calends (Kalendae) were the first days of each month. The name is derived from the Greek word καλειν, to announce, which may initially have been used in the ancient lunar calendar to “announce” the day of the New Moon (or the first sliver of the Waxing Crescent Moon).
- Ides (Idus) occurred one day before the middle of each month. Depending on the month's length, it fell on the 13th or 15th day. In the lunar calendar, the Ides marked the day of the Full Moon.
- Nones (Nonae) fell on the 7th day of 31-day months and on the 5th day of 29-day months, marking the day of the First Quarter Moon.
These markers were used to number the days in each month, counting backward from the upcoming Calends, Ides, or Nones. The count always included the day of the marker. For example, the 11th day of Martius would be known as “Five Ides” to the Romans because it is the fifth day before the Ides of Martius, which fell on the 15th day.