One Day in Prophecy Equals One Year
In Bible prophecy one day equals one year.
After the number of the days in which ye searched the land, even forty days, each day for a year, shall ye bear your iniquities, even forty years, and ye shall know my breach of promise.
- Numbers 14:34 (KJV)
And when thou hast accomplished them, lie again on thy right side, and thou shalt bear the iniquity of the house of Judah forty days: I have appointed thee each day for a year.
- Ezekiel 4:6 (KJV)
For example, take Daniel's 70 weeks (490 days) prophecy. If you add 490 days to 457 BC (decree to rebuild Jerusalem), nothing happens. It makes absolutely no sense. But when you apply the "one day = one year" rule, all of a sudden it makes perfect sense.
Here are some more examples of prophetic times:
1 week = 7 days = 7 years
1 month = 30 days = 30 years
1 year = 360 days = 360 years
time = 360 days = 360 years
times = 720 days = 720 years
half a time = 180 days = 180 years
Jesus also used this principle to describe His own ministry.
And he said unto them, Go ye, and tell that fox, Behold, I cast out devils, and I do cures to day and to morrow, and the third day I shall be perfected. Nevertheless I must walk to day, and to morrow, and the day following: for it cannot be that a prophet perish out of Jerusalem.
- Luke 13:32-33 (KJV)
Jesus' ministry was about three years.
But what about the verse below?
But, beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day.
- 2 Peter 3:8 (KJV)
This is actually just a figure of speech, and not a prophetic rule.
Let's look at that verse in context.
But, beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day. The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance.
- 2 Peter 3:8-9 (KJV)
So, Jesus said that He would come back "soon", but that was 2,000 years ago. So "soon" with the Lord might actually take some time.
The above concept is also mentioned in the book of Psalms.
For a thousand years in thy sight are but as yesterday when it is past, and as a watch in the night.
- Psalms 90:4 (KJV)
Conclusion
Once you start applying the prophetic rule that one day equals one year, all the other time-based prophecies fall into place as well.