Lunchtime Napkin Math – Spirit vs Int Regen

For those of you directed here from Wowhead, this is an old post based off of pre-cataclysm numbers. For Cataclysm spirit/int relationship calculations please head to one of these two pages:

I was pondering some numbers from the Elitist Jerks board and it did get me thinking about the value of Spirit as it stands right now at level 85 in cataclysm. While mana should always be an issue when we raid, we still need an economical way to approach our regen.

I can’t take credit for the notion behind this example as it came from GreenTouch over at the EJ forums:

Currently one Rejuvenation costs us 3725 mana. If you divide that by 12 you find out how much mp/5 is required to recoup that cost over one full minute. In this case it is 310.4 mana or 310 mp/5. In order to achieve 310 mp/5 you would need roughly 620 spirit. Even with the increased amount of stats on our gear that still would take you 2 or 3 pieces of gear just to achieve a 1 Rejuvenation per minute regeneration rate. This is using: 1pt spirit = 0.5 mp/5

Let us comparatively look at our regeneration tied to intellect to calculate an equivalent weight. I am not aware of a new conversion so I might mistakenly use 1 int = 15 mana and talents being multiplicative for the purposes of my math. If someone spots a mistake or incorrect assumption I will gladly revamp my math.

To check the mana gained per point of int (using Furor, HotW, MotW, Leather Mastery): 1*(1.06)*(1.05)*(1.05)*(15*1.15)= 20.16 mana. For int based regen per minute I am using the following statistics: 8 ppm Revitalize, 1/3 Innervate return, and 100% uptime on Replenishment. This yields: 6.66% innervate + 24% revitalize + 6% replenishment for a total of 36.66%. That 1 point of intellect will provide 20.16 mana as well as 7.4 mana per minute. This would put each point of int at .62 mp/5 not including the benefit of the initial mana gain and inherent spellpower gain.


Including the max mana increase from that 1 point of int your math changes a bit depending on the length of combat:

1 minute: 2.30 mp/5

2 minutes: 1.46 mp/5

3 minutes: 1.18 mp/5

6 minutes: .90 mp/5

With one point of spirit at approximately 0.5 mp/5 and one point of int yielding 0.90 mp/5 it is hard to opt for spirit in any situation where we could also have int. The balance I can only assume is that they wanted to be able to add more regen to healer gear without the risk of inflating spellpower for either caster or healer and I respect that design choice. The difficulty would arise in gem,enchant, and reforging choices where a player might want to choose one over the other or opt to reduce spirit. With int offering a lot more by way of starting mana pool and spellpower it seems to win out in the end. For spirit to really shine as a healer stat it needs to be beefy so that with later tiers of gear we actually feel empowered with all of that spirit we have. If it continues to be weak (and I consider 620 spirit to regen one rejuv. weak) then you may see druids reforging a chunk of their spirit away for haste, crit, or mastery.

EDIT: Corrected math to include leather mastery per Hamlet’s comment as well as Revitalize ppm down to 8.

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9 responses to “Lunchtime Napkin Math – Spirit vs Int Regen

  1. I’ll be posting more on this as EJ as usual, but just as a quick note, I think people are too surprised by the fact that Int is so much better than Spirit for mana. They’ve clearly made primary stats (Int/Agi/Str/Stam) stand out for everyone, whereas secondary stats generally compete only with each other. You should be expecting to favor Int in every situation possible in Cataclysm.

    As far as math (just for your future reference): remember to include Armor Specialization (5%) when working with Int. Also, 1 Spi = 0.5 MP5 is an estimate that only holds true at a certain level of Int. Eh, I’ll just check now *pause* . . . at 3575 Int. So at level 80 Int values, Spirit will be worth more than that.

    • I greatly appreciate your input, and I’ll correct the numbers to include the 5% increase from mastery.

      I suppose we shouldn’t be surprised that Int is superior to Spirit as a regen stat. My only real concern is that Spirit is being sold to us as a regen stat that we are intended to invest in when mana is a concern to us. If something is going to be touted as the “healer stat” that helps supplement our mana regeneration I kind of hoped that it would provide more of a boost.

      This blog post wasn’t intended to be negative on Spirit as a whole though. I like the idea of netting a real substantial return for getting my Spirit higher but I am not sure yet just what percent of our overall regeneration it will account for. Time will tell :)

  2. great post! S o it is safe to say that in Cata Intellect will be the main stat for us healing Druids, as well as for regen as for SP.

    • Spirit will always be useful though. Remember that spirit does scale in strength relative to your intellect so having both is always a good thing. My goal was more to shed light on just how powerful intellect is for our regeneration as well as open up the discussion on how we plan to gem/enchant our gear. If you’re going to use a gem or enchant that offers spirit you need to know what you are getting from that bonus relative to any alternatives that give intellect instead.

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  4. Spirit regen depends not only on Int, but on the base regen coeficient as well and that coeficient changes with level. For level 80 since patch 3.1 it is 0.003345 , but it will be different for level 85. The only calculation I was able to find is here, but I have some doubts about the math. It would be nice if you could check this on beta if you will have some spare time.
    If the coeficient is indeed 0.00549 than, with Cata values of Int, spirit regen would be a lot more than 0,5 mp5 for 1 Spi.

    • That is the danger of napkin math, I am reliant on the numbers quoted from some of the seasoned theorycrafters. While I have a background in advanced mathematics I don’t really put it to good use these days.

      Using the formula “Spirit regen = 3 * (0.001 + sqrt(Int) * Spirit * LevelRegen)”. I am a little surprised to see on that link the base regen value calculated so high as in the past it has gone down noticeably over the five levels leading up to max level (e.g. level 75 is listed as .0072 and level 80 as .0055). If this multiplier has in fact not dropped that much then my math would need to be adjusted. From Hamlets post above I can only assume that he has a spreadsheet at the ready to evaluate those values and if he has 1 spirit = .5 mp/5 with Int at 3575 that puts that value at roughly .00279 unless i’ve made a an error in my quickly done excel sheet.

      There isn’t much use in worrying too much about this until 85, the goal was to educate people about the value of int for regen even if it isn’t new news to some.

  5. Any chance of updating these numbers for the patches? I found this information during 4.0.3 and found it very useful, but the numbers for Revitalize confused me until I remembered the 4.0.1 numbers. How much change will the new Revitalize cause? I haven’t done any serious math, but I’d guess the PPM is about half of what was listed before. If we guess a flat 4 PPM and factor in the reduction to 2% mana gained, that means Revitalize returns roughly 8%? It cannot be more that 10%, what with 5 PPM being near impossible. 8% down from 24% might cause the numbers to change concerning Int versus Spirit. Sorry if this is common knowledge already!

  6. No need to apologize at all! I keep seeing links to this old post under wowhead’s Flask of the Draconic Mind when people were debating the use of that versus a spirit flask for raiding. I can definitely do an update to these numbers (to a degree) in the future, my recent posts that breakdown the relationship between spirit and intellect do a slightly better job though it still requires some fine tuning.

    In the newer post I added in a few of the variables that were omitted in this post. One of which is spirit increasing in effectiveness based on how much intellect you have (creating a dependency) and an increase in intellect providing pure intellect based regen as well as boosting your spirit regeneration marginally as well. Going to my home page will get you pretty close to the posts but here are the links:

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