Old Calendar vs New Calendar in Orthodoxy

Old Calendar vs New Calendar in Orthodoxy

Why do some Orthodox Christians celebrate Christmas on December 25 while others celebrate it on January 7?

Why can Saint Nicholas Day be December 6 in one Orthodox parish and December 19 in another?

Why do churches using different calendars often celebrate Pascha on the same Sunday?

The answer lies in the relationship between the Julian calendar, the Gregorian calendar, and the Revised Julian calendar.

The subject can seem complicated because several different issues are often mixed together:

• Liturgical dates
• Civil dates
• Fixed feast days
• The movable Paschal cycle
• Old Calendar and New Calendar terminology

The simplest explanation is this: Old Calendar Orthodox churches generally retain the Julian calendar for fixed feasts, while many New Calendar Orthodox churches use the Revised Julian calendar. The two systems currently place fixed feasts 13 civil days apart.

Old Calendar vs New Calendar: Quick Answers

What Is the Old Calendar in Orthodoxy?

In Orthodox conversation, Old Calendar usually means the continued use of the Julian calendar for fixed feast days.

The Julian calendar was introduced in the Roman world under Julius Caesar and became the calendar inherited by the early Christian Church.

It remained the dominant calendar of the Byzantine Christian world for centuries.

Why Is It Called the Old Calendar?

It is called the Old Calendar because it predates later calendar reforms.

The term distinguishes it especially from:

• The Gregorian calendar
• The Revised Julian calendar

What Is the Julian Calendar?

The Julian calendar was introduced in 45 BC under Julius Caesar.

Its basic rule is simple:

Most years contain 365 days, while every fourth year is a leap year.

This system is very close to the actual solar year, but not perfectly accurate.

What Is the Problem With the Julian Calendar?

The Julian calendar makes the average year slightly too long.

The difference is only a few minutes per year, but over many centuries those minutes accumulate.

As a result, calendar dates gradually drift relative to the astronomical seasons.

What Is the Gregorian Calendar?

The Gregorian calendar was introduced in 1582 under Pope Gregory XIII.

Its purpose was to correct accumulated drift in the Julian calendar and create a more accurate leap-year system.

How Does the Gregorian Calendar Handle Leap Years?

Like the Julian calendar, years divisible by four are normally leap years.

However, century years are treated differently.

A century year is only a Gregorian leap year if it is divisible by 400.

For example:

• 2000 was a leap year
• 2100 will not be a Gregorian leap year
• 2200 will not be a Gregorian leap year

Why Did Orthodox Churches Not Simply Adopt the Gregorian Calendar?

The Gregorian reform originated in Western Europe within the Roman Catholic world.

Orthodox Churches did not universally adopt it for ecclesiastical use.

Different Orthodox Churches therefore continued using the Julian calendar for varying lengths of time.

In the twentieth century, another solution was introduced: the Revised Julian calendar.

What Is the Revised Julian Calendar?

The Revised Julian calendar is a twentieth-century calendar system developed for use within Orthodox Christianity.

It was introduced in connection with an inter-Orthodox congress held in Constantinople in 1923.

Why Was the Revised Julian Calendar Created?

Its purpose was to produce a calendar more closely aligned with the astronomical year while allowing Orthodox Churches to reform fixed feast dates without simply adopting the Roman Catholic Gregorian calendar as their ecclesiastical calendar.

Is the Revised Julian Calendar the Same as the Gregorian Calendar?

No.

The two calendars use different long-term leap-year rules.

However, their dates currently coincide.

How Long Will Revised Julian and Gregorian Dates Remain the Same?

Their fixed calendar dates coincide for many centuries.

The first future divergence occurs in the year 2800 because the two systems treat that leap year differently.

What Does New Calendar Mean in Orthodoxy?

In ordinary Orthodox usage, New Calendar usually refers to the Revised Julian calendar used for fixed feast days.

Therefore:

• Old Calendar = usually Julian
• New Calendar = usually Revised Julian

Is “New Calendar” Always the Revised Julian Calendar?

In everyday Orthodox discussion, usually.

However, terminology can sometimes be used loosely.

This is why it is more precise to say:

• Julian calendar
• Revised Julian calendar
• Gregorian calendar

when discussing technical calendar differences.

What Does Old Style and New Style Mean?

The expressions Old Style and New Style are also used when comparing dates.

Old Style generally means a date according to the Julian calendar.

New Style generally refers to its corresponding date under the modern civil calendar.

Why Is There a 13-Day Difference?

During the twentieth and twenty-first centuries, the Julian calendar is 13 days behind the Gregorian civil calendar.

This means:

Will the Difference Always Be 13 Days?

No.

The calendars use different leap-year rules.

After the year 2100, the difference between the Julian and Gregorian calendars will increase to 14 days.

Will Orthodox Christmas Eventually Move From January 7?

For communities continuing to use the Julian calendar, yes.

Julian December 25 currently corresponds to Gregorian January 7.

After the calendar difference increases, Julian December 25 will eventually correspond to January 8 on the Gregorian civil calendar.

This illustrates why January 7 is not itself the actual liturgical date of Christmas.

Is Orthodox Christmas Really January 7?

Not exactly.

The liturgical feast is December 25.

For Orthodox Churches using the Julian calendar, Julian December 25 currently falls on Gregorian January 7.

Why Do Some Orthodox Christians Celebrate Christmas December 25?

Orthodox jurisdictions using the Revised Julian calendar celebrate the Nativity on December 25 of the modern civil calendar.

Why Do Others Celebrate Christmas January 7?

Orthodox Christians using the Julian calendar celebrate the same liturgical feast on Julian December 25.

That date currently corresponds to Gregorian January 7.

Are December 25 and January 7 Two Different Orthodox Christmases?

No.

They represent the same liturgical feast under different calendar systems.

Both groups celebrate:

the Nativity of Jesus Christ on December 25 according to the calendar they follow.

Do All Orthodox Christians Celebrate Christmas on January 7?

No.

Many Orthodox Christians celebrate Christmas on December 25.

Others celebrate Julian December 25, which currently falls on January 7 of the civil calendar.

Which Orthodox Churches Use the Old Calendar?

Several Orthodox Churches and communities continue to use the Julian calendar for fixed feast days.

Examples include significant parts of Orthodox Christianity associated with:

• The Russian tradition
• The Serbian tradition
• The Georgian tradition
• The Patriarchate of Jerusalem
• Mount Athos

Local and jurisdictional circumstances can be more complex, so parish calendars should always be checked directly.

Which Orthodox Churches Use the New Calendar?

Many Orthodox jurisdictions use the Revised Julian calendar for fixed feasts.

This is common in several Orthodox Churches associated with:

• Greek traditions
• Romanian Orthodoxy
• Bulgarian Orthodoxy
• Other jurisdictions that adopted calendar reform

Calendar usage can also vary within some jurisdictions or dioceses.

Does the Orthodox Church in America Use the Old or New Calendar?

Orthodox parish practice in North America can vary.

Many parishes use the Revised Julian calendar for fixed feasts, while Old Calendar usage also exists within Orthodox communities.

For practical worship, always follow the calendar published by your parish.

Can Two Orthodox Churches in the Same City Celebrate Christmas on Different Dates?

Yes.

One parish may follow the Revised Julian calendar while another follows the Julian calendar.

Both can still belong to canonical Orthodox traditions.

Does Calendar Choice Change Orthodox Doctrine?

No.

The calendar determines when a fixed feast is celebrated on the civil calendar.

It does not change:

• Who Jesus Christ is
• The meaning of the Nativity
• The Resurrection
• The Theotokos
• The saints
• The sacraments

Are Old Calendar and New Calendar Orthodox Christians in Different Religions?

No.

Calendar use by itself does not create a different Christian faith.

Canonical Orthodox Churches can use different calendars while sharing Orthodox doctrine and sacramental life.

Is the Old Calendar More Orthodox?

The Julian calendar has a much longer historical connection with Byzantine and Orthodox Christian life.

For that reason, some Christians strongly prefer it.

Other Orthodox Churches regard the Revised Julian calendar as a legitimate reform of civil feast dating.

The question has produced serious controversy, but it should not be reduced to the idea that one calendar mechanically makes a person more or less Orthodox.

Is the New Calendar a Catholic Calendar?

Not precisely.

The Revised Julian calendar is not technically the Gregorian calendar.

Its fixed dates currently coincide with Gregorian civil dates, but the mathematical systems are different.

Why Does This Confusion Persist?

Because today:

Revised Julian December 25 = Gregorian December 25.

To an ordinary observer they look identical.

The difference only becomes visible when examining their long-term leap-year rules.

Old Calendar vs New Calendar Fixed Feasts

Calendar differences are easiest to understand with fixed feast days.

Old Calendar vs New Calendar Saint Days

The same relationship applies to many fixed saints' days.

Does Saint Nicholas Have Two Different Feast Days?

Not simply because one calendar says December 6 and another says December 19.

Those two civil dates represent the same liturgical December 6 under different calendars.

Old Calendar and Orthodox Name Days

Calendar choice also affects Name Days.

If your Patron Saint has a fixed feast, your civil Name Day date depends on the calendar followed by your parish.

Example: Nicholas Name Day

A person whose Patron Saint is Saint Nicholas of Myra may celebrate:

• December 6 in a New Calendar parish
• December 19 civil date in an Old Calendar parish

The saint and liturgical feast are the same.

Example: George Name Day

The Great Martyr George is commemorated liturgically on April 23.

This currently corresponds to:

• April 23 — New Calendar
• May 6 — Old Calendar civil date

Which Calendar Should I Use for My Name Day?

Use the calendar followed by your Orthodox parish and jurisdiction.

This keeps your personal observance aligned with the community in which you worship.

Old Calendar vs New Calendar and Pascha

This is where the subject becomes more complicated.

The fixed calendar and the calculation of Pascha are separate questions.

Do New Calendar Orthodox Churches Use the New Calendar for Pascha?

Many do not.

Many Orthodox jurisdictions using the Revised Julian calendar for fixed feasts continue to use the traditional Orthodox Paschal calculation.

This means they may celebrate:

• Christmas according to the Revised Julian calendar
• Pascha according to the traditional Orthodox Paschal cycle

Why Can Old Calendar and New Calendar Orthodox Christians Celebrate Pascha Together?

Because many Orthodox Churches retain a common Paschal calculation even when they use different calendars for fixed feasts.

This allows Christmas to fall on different civil dates while Pascha can still be celebrated on the same Sunday.

Is Orthodox Pascha Always Different From Western Easter?

No.

Some years the dates coincide.

Other years they differ.

Why Does Orthodox Pascha Sometimes Differ From Western Easter?

The difference comes from the calendar and computational traditions used to determine the movable feast.

Orthodox Paschal calculation historically retains a traditional ecclesiastical computus connected with the Julian calendar.

Is Pascha Simply the First Sunday After Jewish Passover?

No.

This is a common oversimplification.

The traditional Paschal calculation is an ecclesiastical mathematical system rather than a yearly check of the modern Jewish Passover calendar.

Do All Orthodox Churches Use Exactly the Same Paschal Calendar?

Most Eastern Orthodox Churches share the traditional Paschal calculation, but Orthodox practice is not completely identical everywhere.

This is another reason to follow the calendar of your own parish rather than assume every Orthodox jurisdiction uses the same civil dates for every celebration.

Fixed Cycle vs Paschal Cycle

Does Great Lent Begin on Different Dates for Old and New Calendar Christians?

If Orthodox jurisdictions share the same Paschal calculation, Great Lent will also begin together because Lent is calculated backward from Pascha.

Does Pentecost Change With the Fixed Calendar?

Pentecost belongs to the movable Paschal cycle.

It is calculated in relation to Pascha rather than a fixed monthly date.

Does the Apostles' Fast Depend on Both Calendars?

Yes, and this creates an interesting interaction.

The beginning of the Apostles' Fast is movable because it follows Pentecost and All Saints.

Its end is connected with the fixed feast of Saints Peter and Paul.

Because fixed calendar usage differs, the practical length of the Apostles' Fast can also differ between calendar traditions.

What About the Nativity Fast?

The Nativity Fast is connected with the fixed feast of the Nativity of Christ.

Its civil dates therefore differ between Old and New Calendar communities while preserving the same liturgical relationship to Christmas.

Old Calendar Christmas Fast

For a community using the Julian calendar, the fast leads toward Julian December 25, currently January 7 on the Gregorian civil calendar.

New Calendar Christmas Fast

For a community using the Revised Julian calendar, the Nativity Fast leads toward December 25 on the modern civil calendar.

What About the Dormition Fast?

The Dormition Fast is attached to the fixed feast of the Dormition.

Therefore its civil dates also differ according to calendar usage.

Does Calendar Choice Affect the Twelve Great Feasts?

It affects the civil dates of the fixed Great Feasts.

The movable Great Feasts remain tied to Pascha.

Which Great Feasts Are Fixed?

• Nativity of the Theotokos
• Exaltation of the Holy Cross
• Entry of the Theotokos into the Temple
• Nativity of Christ
• Theophany
• Meeting of the Lord
• Annunciation
• Transfiguration
• Dormition

Which Great Feasts Are Movable?

• Entry of the Lord into Jerusalem
• Ascension
• Pentecost

Does Calendar Choice Affect Feast Icons?

No.

The calendar changes the civil date on which the feast is celebrated.

The sacred subject and traditional icon remain the same.

Example: Nativity Icon

Whether Christmas is celebrated on civil December 25 or January 7, the traditional feast icon remains the Nativity of Christ Icon.

Example: Theophany Icon

Whether Theophany is observed on January 6 or January 19 civil date, the feast commemorates the Baptism of Christ and uses the same traditional Theophany iconography.

Example: Dormition Icon

New Calendar Christians may celebrate Dormition on August 15.

Old Calendar Christians currently celebrate Julian August 15 on civil August 28.

The Dormition Icon and theological meaning remain unchanged.

Should a Home Prayer Corner Follow Old or New Calendar Dates?

Follow the calendar used by the parish where you worship.

If your family comes from more than one Orthodox tradition, you may encounter both systems.

Can a Family Observe Traditions From Both Calendars?

Orthodox families sometimes include members from different cultural or jurisdictional backgrounds.

Family customs can reflect that history.

For participation in parish worship, however, the parish calendar provides the clearest practical reference.

Why Is Calendar Reform Controversial?

The calendar question became controversial because liturgical time is deeply connected with:

• Tradition
• Church authority
• Local identity
• Historical continuity
• Unity of worship

Some Orthodox Christians viewed calendar reform as unnecessary or disruptive.

Others regarded reform as a practical correction that did not change Orthodox doctrine.

Did Everyone Accept the Revised Julian Calendar?

No.

Its adoption was uneven.

Some Orthodox Churches adopted it.

Others retained the Julian calendar.

The result is the mixed calendar landscape that exists in Orthodoxy today.

Who Are Old Calendarists?

This term requires care.

Not every Orthodox Christian who follows the Julian calendar is an Old Calendarist in the ecclesiastical sense.

Is an Old Calendar Church the Same as an Old Calendarist Group?

No.

Canonical Orthodox Churches can legitimately continue using the Julian calendar.

The term Old Calendarist can also refer specifically to movements that separated from established Orthodox hierarchies over calendar reform and related ecclesiastical issues.

Therefore, simply saying that a parish uses the Old Calendar does not tell you its canonical status.

Does Using January 7 for Christmas Mean a Church Is Old Calendarist?

No.

Many canonical Orthodox Churches celebrate the Nativity according to the Julian calendar.

Can a New Calendar Parish Still Be Fully Traditional Orthodox?

Yes.

Calendar usage does not determine whether a parish follows traditional Orthodox theology, liturgy, or iconography.

Can an Old Calendar Parish Still Use Modern Civil Dates?

Yes.

A parish can communicate with the ordinary civil Gregorian calendar while calculating its fixed liturgical celebrations according to the Julian calendar.

Why Do Orthodox Calendars Sometimes List Two Dates?

You may see a saint or feast written like this:

December 6 / December 19

This usually means:

• December 6 — Julian liturgical date
• December 19 — current Gregorian civil equivalent

Which Date Is the “Real” Date?

That depends on what is being described.

Liturgically, an Old Calendar church is celebrating December 6.

Civilly, the surrounding society's calendar says December 19.

Both numbers describe the same day under different calendar systems.

How to Convert Old Calendar to New Calendar Dates

For twentieth- and twenty-first-century dates, a simple conversion for fixed feast dates is:

Add 13 days to a Julian date to find its current Gregorian civil equivalent.

Examples of Old Calendar Date Conversion

Can I Always Add 13 Days?

No.

The 13-day rule is valid for the current historical period.

The difference changes over long periods because the calendars have different leap-year systems.

What Happens in 2100?

The Gregorian calendar will not treat 2100 as a leap year.

The Julian calendar will.

After that adjustment, the difference between the two calendars will become 14 days.

Why Is This Important?

It demonstrates that dates such as January 7 are not permanent Orthodox feast dates.

They are temporary civil equivalents of Julian liturgical dates.

Old Calendar vs New Calendar for Beginners

The simplest way to remember the difference is:

Which Orthodox Calendar Should I Follow?

If you regularly attend an Orthodox parish, follow the calendar used by that parish and its jurisdiction.

This will keep your:

• Feast days
• Fasting periods
• Name Days
• Saint commemorations
• Holy Week
• Parish services

aligned with the worshipping community.

What If I Visit a Parish Using a Different Calendar?

Follow the services and feast being celebrated by the parish you are visiting.

The calendar difference does not prevent Orthodox Christians from recognizing the same sacred events and saints.

What If My Family Uses One Calendar and My Parish Another?

This is increasingly common in multicultural Orthodox communities.

You may preserve family traditions while following your parish calendar for regular liturgical worship.

Can Children Understand the Two Calendars?

Yes.

A simple explanation is:

“The Church feast has one liturgical date, but different calendars can place that date on different days of the civil calendar.”

Using Icons to Explain the Calendar Difference

Icons make the distinction particularly clear.

Show the same Nativity Icon and explain:

• One parish celebrates it on December 25
• Another celebrates it on January 7
• Both are celebrating the same Nativity of Christ

Common Myths About Old Calendar and New Calendar Orthodoxy

Myth: Orthodox Christmas Is January 7.

Not exactly.

Julian December 25 currently corresponds to Gregorian January 7.

Myth: All Orthodox Christians Celebrate Christmas January 7.

No.

Myth: Orthodox Christians Who Celebrate December 25 Are Using the Roman Catholic Calendar.

Not necessarily.

Many use the Revised Julian calendar.

Myth: Revised Julian and Gregorian Calendars Are Exactly the Same.

No.

Their dates currently coincide, but their long-term leap-year rules differ.

Myth: Old Calendar Christians Celebrate Saint Nicholas Twice.

No.

December 6 Julian currently corresponds to December 19 Gregorian.

Myth: January 7 Will Always Be Orthodox Christmas.

No.

Myth: Old Calendar and New Calendar Christians Believe Different Things About Christmas.

No.

Myth: A Church Using the Julian Calendar Is Automatically an Old Calendarist Schismatic Group.

No.

Many canonical Orthodox Churches use the Julian calendar.

Myth: New Calendar Orthodox Churches Use the Gregorian Calendar for Everything.

No.

Many use the Revised Julian calendar for fixed feasts while retaining the traditional Orthodox Paschal cycle.

Myth: Calendar Difference Always Means Different Pascha Dates.

No.

Old Calendar vs New Calendar FAQ

What is the Orthodox Old Calendar?

The Old Calendar generally means the Julian calendar used for fixed Orthodox feast dates.

What is the Orthodox New Calendar?

It usually means the Revised Julian calendar used for fixed feast dates.

What is the current difference between them?

For fixed dates in the twenty-first century, the Julian calendar is 13 days behind the modern Gregorian civil calendar.

Why is Orthodox Christmas January 7?

Julian December 25 currently corresponds to Gregorian January 7.

Do some Orthodox Christians celebrate Christmas December 25?

Yes.

Are December 25 and January 7 different Christmas feasts?

No.

They are the same liturgical December 25 expressed through different calendar systems.

Why is Orthodox Theophany sometimes January 19?

Julian January 6 currently corresponds to Gregorian January 19.

Why is Saint Nicholas sometimes celebrated December 19?

Julian December 6 currently corresponds to Gregorian December 19.

Why is Saint George sometimes celebrated May 6?

Julian April 23 currently corresponds to Gregorian May 6.

Does the New Calendar mean Gregorian calendar?

Usually not precisely. Orthodox New Calendar usage normally refers to the Revised Julian calendar.

Are Revised Julian and Gregorian dates currently the same?

Yes, for fixed dates in the present era.

Will they always remain the same?

No. Their mathematical systems eventually diverge.

Will the Julian and Gregorian difference always be 13 days?

No. It will increase to 14 days after the year 2100.

Do Old Calendar and New Calendar Orthodox Christians celebrate Pascha together?

Many do because they share the traditional Orthodox Paschal calculation.

Does calendar choice change Orthodox theology?

No.

Can canonical Orthodox Churches use the Old Calendar?

Yes.

Can canonical Orthodox Churches use the New Calendar?

Yes.

Which calendar should I follow?

Follow the calendar used by the Orthodox parish and jurisdiction where you worship.

Old Calendar vs New Calendar: The Short Answer

The Orthodox Old Calendar generally means the Julian calendar.

The Orthodox New Calendar generally means the Revised Julian calendar.

During the twenty-first century, fixed Julian dates currently fall 13 days later on the modern civil calendar.

That is why:

• Julian December 25 = Gregorian January 7
• Julian January 6 = Gregorian January 19
• Julian March 25 = Gregorian April 7
• Julian August 15 = Gregorian August 28
• Julian December 6 = Gregorian December 19

Many New Calendar Orthodox Churches use the Revised Julian calendar for fixed feasts while still using the traditional Orthodox Paschal calculation.

This explains why two Orthodox parishes may celebrate Christmas on different civil dates but celebrate Pascha together.

The calendar changes the civil date of a celebration. It does not change the Nativity, Resurrection, saints, feast icons, or Orthodox faith being celebrated.

Explore the Orthodox Calendar at Mercy Fold

Continue with Mercy Fold's related guides:

• Orthodox Calendar
• Orthodox Calendar 2027
• Orthodox Liturgical Year Explained
• Orthodox Feast Days
• The Twelve Great Feasts of the Orthodox Church
• Orthodox Saints Calendar
• Orthodox Name Days: Dates, Saints and Traditions
• Best Icons for Christmas
• Best Icons for Pascha
• Icons for Feast Days
• Orthodox Saints FAQ
• Orthodox Iconography FAQ

Use this guide to understand why Orthodox feast dates sometimes differ, then follow Mercy Fold's calendar, feast, saints, and icon guides to explore the events celebrated on those dates and the traditional Orthodox images associated with them.