I saw the original question and the requests to specify a vocation and a time frame. However, I don't see a need for these changes. If you're going to calculate it for a certain vocation, you can easily do it for all other vocations. In a similar way, if you can calculate it for a fixed time frame, you can also calculate it based on the current time. So, I went ahead and made a spreadsheet for this.
The first information we need is that the magic level rate on offline training is equal to 50% of the mana regeneration rate of your promoted vocation. It means that, for every minute of offline training, you will advance half of the amount of mana you would regen by eating ordinary food if you were online (and promoted) with no item/event/resting area bonus. You can see the base mana regeneration rate values for each vocation on the table below. Since, for every minute of offline training you need one minute to regen it, we must divide the regeneration rate values by 4 in order to determine the average amount of skill points gained by offline training per minute, as shown on the table below.
Vocation | Mana regen per min | Avg skill pts per min |
---|
EK | 20 | 5 |
RP | 40 | 10 |
ED/MS | 60 | 15 |
Then, we need to determine the amount of minutes between now and July 11, 2012 (when the offline training was implemented). This can easily be done with a spreadsheet function. Additionally, we can add the total time of Double Skills Events (162 days) to your calculation as if they were extra days. With the average amount of skill points per minute and the total amount of minutes, we can determine the amount of gained skill points by multiplying these two values.
Finally, with the Skill Equations, we can determine the final Magic Level of each vocation after offline training since July 11, 2012 till today. Based on the time I'm writing this answer, the magic level for each vocation are the following, however, you can check my Offline Training Magic Level Calculator Spreadsheet which is based on the "current time" whatever it is when you open/refresh it.
Vocation | Magic Level |
---|
EK | 9 + 32.9% |
RP | 28 + 14.3% |
ED/MS | 89 + 13.6% |
Out of curiosity, without considering the double skill events, the values would be the following:
Vocation | Magic Level |
---|
EK | 9 + 29.2% |
RP | 28 + 2.5% |
ED/MS | 88 + 65.1% |