Why do commentators calculate the time periods in Revelation based on a 30 day month?

Question

Most people interpret the 1260 days in Revelation on a 30 day month.(Rev 12:6) The 1260 days= 42 months.(Rev 13:5) 1260 days divided by a 30 day month= exactly 42 months.

Why is this interpretation used?

Answer 1

There is no straight-forward answer to this so I will offer two suggestions. But first the facts. The prophecy of 1260 days in its various forms occurs (significantly) seven times in Scripture.

• Dan 7:25 - 3½ times (years) saints persecuted by little horn
• Dan 12:7 - 3½ times (years) end marks the beginning of the end of time
• Rev 11:2 - 42 months gentiles trample on the holy city
• Rev 11:3 - 1260 days two witnesses prophesy in sackcloth
• Rev 12:6 - 1260 days woman flees to the desert to escape the dragon
• Rev 12:14 - 3½ times (years) woman out of dragon’s reach
• Rev 13:5 - 42 months beast blasphemes & exercises defiant authority

[Luke 21:24 Jesus possibly alludes to this 1260 day prophecy by calling it the times of gentiles – see Rev 11:2 where the gentiles trample the Holy City, but this will not be discussed here except to suggest that it is possibly based on Elijah's 3½ years - see Luke 4:25, James 5:17.]

From this, we may observe several things:

• The prophetic calendar appears to be either unrelated to, or a significant modification/simplification of the Jewish calendar. The Jewish ancient calendar did NOT even have 12 months in the year - it had 12 and one third months! The Jewish calendar did NOT have 30 days to the month - it was 29½ days on average.
• This appears to be some kind of special prophetic calendar that might have been a modification of the Egyptian calendar with its 12 months of 30 days plus 5 extra days (the other one quarter of a day was ignored by the Egyptians thus creating the Sothic cycle but this will not be discussed here.)
• This (astronomically unknown) prophetic calendar has 12 months per year, 30 days per month and 360 days per year. This is unrelated to any known calendar, ancient or modern. However, that still appears to be what the above suggests.

There are possibly more interpretations of this time prophecy that exegetes. Most try to be quite precise. However, the imprecision and clear abstraction of the prophetic calendar does not suggest that great precision is warranted by the text itself!