How To Use:

Start by entering your World of Warcraft™ character information on the left form:

• Region: The region where your character lives
• Realm: The realm of your character
• Character Name: Your character’s name
• Target Rating: The Mythic+ Rating you would like to achieve.
• Avoid a Dungeon: Select your least favorite dungeon that you would like to exclude from the results.
• Max Level: The maximum key level you are willing to attempt. (Maximum acceptable value is 30)
• Get the rating this week: When this option is enabled. it will only suggest runs for this week, with the current first affix. If this is disabled, then it will suggest results for both the current week and next week.

Understanding the Results:

Once you successfully enter the information and press submit, this tool will evaluate your current overall rating as well as your rating for each dungeon. with that information it will generate multiple options, from the hardest but fastest to the easiest but longest.

Each option will have the suggested dungeons, the minimum key level, and the minimum time to finish it to get the ratings. If you successfully finished all the suggested keys, you would have the desired rating.

How it Works:

To understand how this tool works, first we need to understand how World of Warcraft™ calculates Mythic+ Rating:

Each key level gives a different "base" score. the following table shows how the base scores are distributed as follows:

The "Base Score" in the above table represent the rating you would get if you finished the dungeon exactly on time. However, you will get more rating (up to the "Max Score" from the table) if you finish the dungeon before it's time limit. Similarly, if you finish the dungeon after the time limit you will get less than the base score (down to the "Min Score"), however if you run time was more than 40% of the time limit then 0 rating is given.

How much rating you get is calculated as follows:
First we need to calculate the run time percentage. The run time percentage is calculated as follows:

where:
T_Limit = The dungeon's time limit.
T_Run = Your dungeon's run time.
Note that the result value is capped at 40% using "Min". i.e. it takes the minimum between the calculated value and 40%.

Using calculated percentage from Eq. 1, we can calculate the run's rating as follows:

where:
P_T = The time percentage calculated in the previous step.
Base_level = The base score for the key level, looked up from the table above.

For example:
if you ran a level 17 key. assuming the time limit for that dungeon is 33 minutes ( = 1980 seconds in total) and you completed it in 27mins and 47 seconds ( = 1667 seconds in total) then the rating for this run can be calculated as follows:

Note that if the result was higher than 40% then we cap it at 40%
Next step is to calculate the dungeon rating:
given that the key level was 17 in this example. we look up the base score to be 149 from the table above.
and 15.81% = 15.81/100 = 0.1581

For calculating overtime runs, it's a very similar process, except, the moment the key is over time, 5 ratings is taken away from the base, and then the rest is taken away depend on the time percentage:

Notes:

1. when calculating P_T here, it's the same exact formula above (Eq. 1), but since the run time is bigger than the time limit then the percentage would be negative, therefore subtracting from the base score
2. If P_T > 40% then 0 rating is given to this dungeon
3. If the key level is 21 or higher, then not timing it will use the base score for a level 20 key. for example, if the key level is 26 and it was over the time limit then Base₂₀ = 170 (and not 212) is used for the calculations

All this is half the story. We cannot forget about the alternating weeks (Tyrannical and Fortified). For each dungeon, you will have 2 ratings, the best rating you got for Tyrannical and another for Fortified. The way they are combined is as follows:

where:
R_Tyr = Your rating for a certain dungeon on Tyrannical.
R_Fort = Your rating for the same dungeon on Fortified.

To continue on the above example, lets assume that the above run was on Tyrannical week, and it was your best run. And also, let us say that your best run on Fortified (for the same dungeon) is a level 16, finished within 35 mins and 15 seconds ( = 2115 seconds in total), note that this is over the time limit. Then the calculations go as follows:
First we calculate the time percentage:

Therefore, the rating should be calculated as:

Note that we subtracted 5 rating because this run was over the time limit as per Eq. 3.
From here we can calculate the overall rating for this particular dungeon as

And that would be your total rating for this particular dungeon. we calculate the rating for each of the different dungeon, and then add up all the ratings to get the total Mythic+ rating.

Note that the best rating for each affix (Tyrannical and Fortified) for each dungeon is the one used for the final mythic rating.

Using the above formulas, this tool applies them backwards. when you set a target rating. the tool fetches all your runs from raider.io and calculates what is the minimum key level and run time required to achieve that over all rating. by giving you options on how many runs are required to achieve the rating
For more details on the entire code, you can find it on github: https://github.com/SamFarah/RatingCalculator