Beckett Grading Service Formula

I've been trying to figure out the Beckett Grading Service (BGS) "formula" in my spare time.  I've been looking at BGS graded cards on eBay and COMC.com to help narrow down the exact "formula" that BGS uses.

For the most part, it's fairly simple.  It goes like this:

• Generally, your final grade can only be 0.5 higher than your lowest subgrade. 
• Exception: If two or more of your subgrades share the lowest subgrade score, then your final grade will be equal to that lowest subgrade.

An example of the general rule would be a card with Centering 9.5, Corners 9.5, Edges 9.5, and Surface 9.0.  The final grade is 9.5.

Another example of the general rule would be a card with Centering 9.0, Corners 8.5, Edges 8.0, and Surface 9.5.  The final grade is 8.5.

An example of the exception to this general rule would be a card with Centering 9.5, Corners 8.5, Edges 8.5, and Surface 9.5.  The final grade is 8.5. 

This general rule and its single exception will probably work for about 99% of BGS graded cards.

Things get a little more complicated, however, when one subgrade is drastically lower than the rest of the subgrades (i.e. a card with Centering 9.5, Corners 9.5, Edges 9.5, and Surface 7).  In such circumstances, the final grade can sometimes be more than 0.5 higher than your lowest subgrade.  For more information about these cards, see this blog post. 

Finally, the subgrade requirement to get a BGS Pristine 10 is very stringent:

• To get a "BGS Pristine 10" final grade, you must have at least three 10 subgrades and any subgrade which isn't a 10 must be a 9.5.  (In other words, you cannot have any subgrades be a 9.0 or lower.)

For example, a card with subgrades of Centering 10, Corners 10, Edges 9.5, and Surface 10, would have a final grade of Pristine 10.

For example, a card with subgrades of Centering 9, Corners 10, Edges 10 and Surface 10, would have a final grade of Gem Mint 9.5.

Just keeping in mind the above general rule and its exception (which will work for what I estimate to be over 99% of BGS graded cards), you will be able to calculate what a card's final BGS grade should be depending on its subgrades.  This knowledge is especially useful if you are thinking about submitting your own cards to Beckett for grading.  By honestly estimating what subgrades your card will receive, you can calculate what your final grade will be based on those subgrades.