Do Spell Ranks have any numerical equivalent?

Question

Looking at Hayate's and Nanoha's spells, some of them are given a rank. For instance, Nanoha's Starlight Breaker is ranked S along with Blast Calamity and Hayate's Ragnarok, while Hayate's (or Reinforce's to be exact) Diabolic Emission is ranked S-

While there is information on Ranks, these seem to only refer to the TSAB's internal Mage Ranking and not how they relate to spells.

I am wondering if the Spell Ranks have any numerical equivalent to them – something similar to The Nasuverse Rankings (in which B = 40, A = 50, and the power after appending +'s is (Rank Value + (Rank Value x No. of +'s)), so A++ = 150).

Answer 1

There are no such numeric formulae; at least, not in the official materials. Numeric rankings are rarely mentioned in the show; one of the rare such examples occurs in an episode of the original series, where Nanoha's magic power is estimated as 1.27 million, while Fate's is 1.43 million. (They were both of AAA rank at the time.) "Plus" and "minus" are not modifiers that can be applied multiple times to a rank, either; "A+" is simply a rank higher than "A" and lower than "AA-".

Mage ranks are qualitative; they do not just measure amount of magic power, but also skill. They are usually granted by a test by TSAB; when this is not possible, i.e. in case of antagonists, they can be estimated. A spell rank presumedly signifies the rank of a mage who should be able to cast the spell, but this isn't a hard and fast rule: "Eternal Coffin" is a S+ rank spell, but Chrono (ranked AAA+) was able to use it thanks to his device's specialization for freezing magic; for another example, Teana (ranked B at the time) was able to use an AA-rank technique during a training to combine her projectiles with a barrier in order to protect them from an anti-magic field.