How long is Jubilee cycle?
The answer is Jubilee is exactly 50 years with 7 cycles of 7 years! It is 50 years from Jubilee to Jubilee.
This is because there are exactly 50 years between 7 Shabbats of years, just like there are 8 days between two Shabbats, even though the week is only 7 days.
Let's look at the difficulty that traditional sources encounter due to misunderstanding of this simple rule above
Here is one good article: http://www.academia.edu/3787394/The_Jubilee_Every_49_or_50_Years
And here is an excerpt from Wikipedia about issues with the Jubilee:
An example of the textual argument is given by North in his comparison of Leviticus 23:15-16 with Leviticus 25:8-11. The first passage establishes the timing, in days, for the Festival of Weeks (Shavuot), while the second prescribes the timing, in years, for the Jubilee. In the first passage, the start of counting for the Festival of Weeks is said to be "the day after the Sabbath" (mimaharat ha-shabat, Leviticus 23:15), and is to end "the day after the seventh Sabbath" (mimaharat ha-shabat ha-sheviyit, Leviticus 23:16). These seven weeks would constitute 49 days in most modern methods of reckoning.
Nevertheless, verse 16 says that they are to be reckoned as 50 days. This method of reckoning (sometimes called "inclusive numbering") is fairly common in Scripture; for example, the Feast of Tabernacles is to last for seven days (Leviticus 23:34-36), but the last day is called the eighth day (v. 36). North found this comparison between Leviticus 23 (Feast of Weeks) and Leviticus 25 (Jubilees) to be "the strongest possible support for the forty-ninth year" as the Jubilee year. His conclusion that the Jubilee was identical with the seventh Sabbatical year was followed by Lefebvre, for this as well as additional reasons.
The consideration that the Jubilee was identical with the seventh Sabbatical year solves the various practical problems, as also addressed by these authors. If the Jubilee were separate from, and following the seventh Sabbatical year, then there would be two fallow years in succession. Lefebvre points out, however, that there is no support in Scripture for two voluntary fallow years in succession, even though some have misinterpreted Leviticus 25:21-22 as if this refers to a Jubilee year following a Sabbatical year, which is not the sense of the passage. Lefebvre shows that this cannot be the case because planting is mentioned for the eighth year; it is the year after a Sabbath, a year in which planting and harvesting resume.
Another practical problem that would occur if the Jubilee cycle were 50 years is that, after the first cycle, the Jubilee and Sabbatical cycles would be out of phase unless the seventh Sabbatical cycle was stretched to eight years. But Scripture gives no instructions for making such an adjustment. Instead, it is assumed that the two cycles will always be in phase so that the shofar can be sounded in the seventh year of the seventh Sabbatical cycle.
In contrast, the consideration that the Jubilee year is an intercalated year separate and distinct from the Sabbatical cycles resolves an issue of the requirement for observation of the Torah of both Leviticus 25:3 and Leviticus 25:11. For in the former passage, the command is that sowing and pruning must occur for 6 consecutive years, whereas in the latter, the command is to neither sow, nor reap nor gather from untended vines in the Jubilee year. If the Jubilee year is the 50th year as confirmed by Leviticus 25:10-11, it must necessarily be a separate year from the first 49 years comprising the whole of the first seven Sabbatical cycles, therefore it cannot be identical with the seventh Sabbatical year as 49 does not equal 50. Were the Jubilee year to be considered identical with year 1 of the following Sabbatical cycle, the requirement of observing 6 consecutive years of sowing and pruning could not be observed as only 5 years would therefore be available for sowing and reaping, not the specified six as Leviticus 25:3 requires.
As you can see, some commentators did indeed produced the correct solution, they just did not know how to explain it.
Here is the diagram of how the Jubilee system works:
Blue circles - Jubilee years
Green circles - Shabbat years
Blank circles - regular years
Basically, we start our count from Shabbat year, since Shabbat cycle of 7 years can't be by itself (it has to be preceded by the Shabbat year). This way we get exactly 50 years between Jubilee and Jubilee. In other words, we count 50th Shabbat year as a Jubilee year at the same time. Please note that there are 49 years from 1st regular year until 50th Jubilee year.
This way, the system works and does not drift like in traditional interpretations.
So, as you can see, it is always important to remember that it is exactly 8 days (not 7) between Shabbat and Shabbat. And in Torah calendar system we ALWAYS COUNT FROM SHABBAT TO SHABBAT !!! We do not start counting events from anything other but Shabbat. This way, all holy days and years fit together very nicely.
It is interesting to note traditional notion that there is a connection between Jubilee and Counting of Omer. This is indeed true and this is exactly where I got my idea and my solution from. Counting of Omer also lasts 50 days (from Shabbat to Shabbat). There are 50 days between 7 Shabbats of the Counting of Omer. Similarly, we have 50 years between Shabbat year and Shabbat year, 50 years between Jubilee and Jubilee.
I hope now it is clear that Jubilee is 50 years long - not 49 years long !!!