How Long is the Tribulation?

It is commonly believed the tribulation lasts for 7 years but the Bible specifically shows us that the tribulation is 3 ½ years. Daniel 7:25, Daniel 12:7, Revelation 11:1-3, Revelation 12:6, Revelation 12:14, and Revelation 13:5 all show that the tribulation lasts for 3 ½ years. Also remember that Jesus said the tribulation would begin after the abomination of desolation in Matthew 24:15-21. Daniel 9:27 shows the abomination of desolation occurs in the midst or middle of the seven years. That would leave 3 ½ years for the tribulation period.