Calendar Insights into Biblical Prophetic

1. Introduction

Calendars of the First Century are different from ours. We cannot use our Gregorian calendar to unlock the prophetic numbers found in Daniel, the Gospels, and the Book of Revelation. None of the numbers related to the Great Tribulation will make sense until they are translated into the author’s relevant calendar.

For example, if we want to understand that there was a moon that turned red on September 8th, 70 CE, the night Jerusalem burned, we need to know that the NASA website providing this data uses the Julian calendar, not the Gregorian calendar. To find the Hebrew date, we first need the Julian date. Alternatively, to determine the dates of the three signs that initiated the 42-month prophecy, we must use the Hebrew Calendar to convert them to the corresponding Julian calendar dates.

Daniel used the Hebrew calendar for his prophecies regarding the 2300-day Great Tribulation. If we interpret Revelation’s five months or its 42-month prophecy using the Julian or Gregorian calendar, we may get confused.

A. Previously

In our lessons on the Great Tribulation, we have answered the questions.

1. When was the Great Tribulation?
2. What was the Abomination of Desolation?
3. Had the gospel been preached to all nations before the Great Tribulation?
4. Why does Revelation equate Jerusalem to Sodom and Egypt?
5. Who was Josephus, and is he a credible historian?
6. What are the Seven Seals?
7. How did the seals relate to the Great Tribulation?
8. Was one quarter of the population killed, as Revelation says?
9. Who were the 144,000? When did this number stop counting?

In this lesson, we will understand the various calendars of the first century.

B. Further Lessons

Then, in the following lessons, we will answer these questions:

1. Who were the armies crossing the Euphrates in Revelation?
2. Was one third of the population killed, as Revelation says?
3. Why did Jesus say His coming would be like lightning from the east to the west?
4. How long was the Great Tribulation — seven years or 2300 days?
5. When did the Great Tribulation begin?
6. When did it end?
7. When did the Christians flee Jerusalem?
8. How many people were killed during the Great Tribulation?
9. Why was there thirty minutes of silence in heaven?
10. When was the forty-two-month prophecy of Revelation?
11. What is the significance of the five-month prophecy in Revelation 9?
12. What was Daniel’s 1290 and 1335-day prophecy about?
13. What is the importance of Antioch in the prophetic calendar?
14. What was the blessing to those who lasted 1336 days?

2. Hebrew Calendar

When Daniel prophesied, he was not using the Roman calendar, as it did not yet exist. Daniel was prophesying in Hebrew in Chapters 1-2:4a and 8-12, and was using the Hebrew calendar. The Hebrew calendar differs from the modern Gregorian and Julian (Roman) calendars.

A. Hebrew Calendar Calculator

I have consulted a leading resource from Utrecht University on all prophecies to improve accuracy. However, we are still looking back 2000 years, so some inaccuracies may occur; overall, we are within a few days of accuracy with this system. I will summarise with some detail, and some readers may wish to verify my calculations for the 2300-day Tribulation; for this reason, I have included them later, along with a spreadsheet.

B. Lunisolar calendar

The Hebrew calendar follows a nineteen-year lunisolar cycle that begins in September. This cycle includes seven leap years occurring in the 3rd, 6th, 8th, 11th, 14th, and 17th years. During a leap year, an extra month is added, usually in March.

C. Months in Hebrew Calendar

The months of the Hebrew calendar are in this table:

D. Leap Years

Each non-lunar year is calculated to be between 353 and 355 days, according to this calendar, while each lunar year spans between 383 and 385 days. Here is a table displaying the number of days and months in each year, along with the leap years during the Great Tribulation.

3. Macedonian Calendar

Josephus relied on the Ancient Macedonian calendar for most of his dates in his historical writings, though not all. It was based on the Babylonian calendar. Similar to the Hebrew calendar, it was lunisolar, with extra months and leap years added to keep in sync with the seasons. The dates generally aligned with the Roman (Julian) calendar, as you’ll see as we work through the lessons.

4. Julian (Roman) Calendar

Julius Caesar introduced a more modern calendar in 46 CE. Because it is solar in origin, it has a leap year every 4th year. However, it gained 3.1 days per 400 years, and was replaced by the Gregorian Calendar in 1582. The international standard is to use the Roman calendar when referring to dates in the first two centuries under consideration. For this reason, we will use the same standard, unless implicitly informed otherwise.

If you are interested in the Gregorian calendar date for any date in the first century CE, add two days. For example, the Julian 15th March 70 CE becomes the Gregorian 17th March 70 CE.

5. Tyre Calendar

This is another relevant calendar, as it seems Josephus occasionally used it. We will only refer to it when it applies to a specific prophecy.

6. Timed Prophecies

We will look at various timed prophecies in this series.

A. Three and a Half Years

These come in various formats:

• Three and a half years,
• A time, times and half a time.
• One thousand two hundred and sixty days

Futurist teaching suggests that these relate to the Great Tribulation. Surprisingly, they do not; instead, they pertain to the period before and after Jesus’ death. We will discuss this in the next lesson.

B. Forty Two Months

This period is mentioned in Revelation as the time when the Gentiles tread down Jerusalem.

But leave out the court which is outside the temple, and do not measure it, for it has been given to the Gentiles. And they will tread the holy city underfoot for forty-two months.

Revelation 11:2

And to make war against the Jews

… and he was given authority to continue for forty-two months. It was granted to him to make war with the saints and to overcome them.

Revelation 13:5,7

This relates to the Great Tribulation, which begins with the three signs mentioned in our lesson on the seven seals. It starts on Nisan 15, 67 CE, and culminates in the destruction of Jerusalem on Elul 14, 70 CE. The three signs are:

• The heifer that produced a lamb,
• The east gate of the Temple opens by itself and
• The bright light lasts for 30 minutes before fading.

Because they do not understand the Hebrew Calendar, futurists have assumed that the 1260 days of Daniel correspond to 42 months in Revelation.

This time period is covered in a later lesson in this series.

C. Five months

They had tails like scorpions, and there were stings in their tails. Their power was to hurt men five months.

Revelation 9:10

These five months span Titus’s siege of Jerusalem from Nisan 15, 70 CE, to its destruction on Elul 14, 70 CE.

D. 2300 days

This is the length of the Great Tribulation, about six years and four months. It is not seven years, as will be explained in the next lesson.

“How long will the vision be, concerning the daily sacrifices and the transgression of desolation, the giving of both the sanctuary and the host to be trampled underfoot?”
And he said to me, “For two thousand three hundred days; then the sanctuary shall be cleansed.”

Daniel 8:13-14

This prophecy spans the entire Great Tribulation. We will find it starts when Nero agrees to attack Jerusalem on December 23, 66 CE, after the Christians have fled Jerusalem. Its end is when the first Jewish-Roman war finishes with the fall of Masada on Passover Nisan 15, 73 CE.

E. 1290 Days

This starts at the same time as the 42-month prophecy, Nisan 15, 67 CE.

“And from the time that the daily sacrifice is taken away, and the abomination of desolation is set up, there shall be one thousand two hundred and ninety days.

Daniel 12:11

It ends immediately after the games celebrating Domitian’s birthday, when 10,000 captives were killed on Cheshvan 4 (27 October) 70 CE.

F. 1335 Days

This final prophecy begins on the same date as the 1290-day and 42-month prophecies (Nisan 15, 67 CE). It ends when the captive Jews finish their march from Jerusalem to Antioch on Kilev 20 (December 13) 70 CE, after Titus proclaims their right to exist as a people.

Blessed is he who waits, and comes to the one thousand three hundred and thirty-five days.

Daniel 12:12

It is in this city that they find the blessing of being protected by other Jews, and many come to Christ, making it the true centre of Christianity, rivalling Rome for the next 1000 years.

7. Summary

Josephus primarily used the Macedonian Calendar, which can be directly converted to the Julian Calendar. Using the Hebrew calendar calculator, we can identify the Hebrew days, months, and years, thereby clarifying the mysteries of these prophecies. For those of us who are not Jewish, this remains a mystery, but to the Jews, it would have made much more sense.

Now that we have learned about the calendars and time periods mentioned in first-century prophecies, we turn to the first of these: 1260 days, or three and a half years. This is not part of the Great Tribulation; instead, it relates to the time of Jesus’s ministry and that of the apostles.

© Use by Permission Awakening Impact Ministries / Dr Neville Westerbeek van Eerten D.Miss, 2026