Stat comparison

Among the most interesting decisions to make in World of Warcraft are those concerning gear. Should a warrior prefer +Stamina or +Dodge%? Is +heal better or mana/5? Of course there can be no "right" answers to such questions. It's always a matter of "it depends...", but sometimes reasonable upper and lower limits can be found (e.g. 5 mana/5 will for all casters always be better than 10 spi). Another helpful insight is the Item Values article, just to see which relative values Blizzard gives to different stats.

Healer mana

There are many aspects to the problem how to optimize a healers endurance. Lets look at the various item stats which can affect healer mana and/or efficiency.

Intellect

Int simply increases the mana pool and spell crit chance. It's the benchmark for the other stats.

Spirit

When considering spi, it is important to understand how mana regeneration works (see 5 second rule). There are mods which collect the data on how much time is spent inside the 5 second rule, and how much mana each point of spirit regenerated (like Spirit versus Intellect). For "average" combats it's safe to assume that 1 spi = 1 int.

Mana/5

At first glance mana/5 is quite similar to spi - it regenerates mana. In combat though mana/5 is usually "better", as a rule of thumb a factor of 3 can be assumed (1 mana/5 = 3 spi)

+heal

Comparing +heal to the other stats is a little tricky. It is necessary to consider current mana efficiency (HP/mana and HP/time) and its change due to +heal. For any given combat thus the saved amount of mana can be found. The effect of additional +heal becomes less after a certain point, because increasing an already high efficiency yields less of an effect than increasing a low efficiency. The various sources agree that a factor of about 8 is appropriate to convert +heal to mana/5 (1 mana/5 = +8 heal).

Spell crit%

Similar to +heal, this increases efficiency (with the added problem that crits may easily result in overheal). One percent crit in theory increases total HP healed by 0.5%, which in turn could be translated to an increase of the available mana by the same amount.

Summary

Reducing all stats to Int leads to the following:

1 Spi    = 1 Int
1 Mana/5 = 3 Int
+8 heal  = 3 Int

In longer fights +heal and mana/5 become more important, when grinding spi and int are preferrable. For PvP, Int is probably the most important stat, because PvP encounters tend to be short but intense, and the increased critrate is important there too.

A very thorough discussion can be found at WoWHealers

Related articles:

• Formula:Healers Shields

Spell damage vs Spell crit

The following reasoning will focus on DPS alone. Taking other factors (like procs off crits) into consideration would be possible, but since there are many such effects, and they are very dependent on class abilities and talents, they will be ignored here. Additionally, spell crits are assumed to increase damage by 100% (not by the normal 50%, but classes interested in this discussion should have taken their talent).

Te following abbreviations will be used:

• crat : crit rating (the crit percentage is the crat / 21)
• pdmg : +damage, the spell damage value added from gear
• bdps : base dps (dps prior to adjustment for crits, including talents and pdmg)
• bep  : break even point (the bdps value at which crat and pdmg yield an equal increase of total DPS)

pdmg and crat are basically multiplied to yield final DPS. Contrary to popular belief, pdmg does *not* really result in a "linear" DPS increase, it's rather just another factor in the product. In principle it's (bdps + pdmg) * crat = final DPS, which means that the pdmg is also multiplied by crat. If we want a product to become as large as possible, but the sum of the factors needs to be constant, it's best if the two factors are equal. Thus in theory, both factors should be increased in parallel.

Assuming a crat of 0, one point of crat increases total DPS by 1 / 2100 of bdps (this equals 0.048%), and one point of pdmg results in an increase of bdps by 1 / 3.5 = 0.286. If we want the two to be equal, we need to do the following calculation:

bep / 2100 = 0.286
bep = 0.286 * 2100 = 600

So at 0% crit chance, we need 600 DPS base damage before crat starts to produce more DPS than pdmg. If we do have some prior crat, the above calculation becomes:

bep / 2100 = 0.286 * (1 + old crat / 2100)
bep        = 600 * (1 + old crat / 2100)
bep        = 600 + (old crat * 600 / 2100)
bep        = 600 + (old crat * 0.286)

This means that for each point of crat we already have, we need 0.286 more DPS in order to make crat and pdmg equal. These 0.286 DPS are exactly what one pdmg yields. In other words, for each point of crat, we also need a point of pdmg to make it viable (and vice versa). The optimal compromise is to have enough +damage gear to bring base DPS to 600, and from this point on an equal amounts of crit rating and plus damage.

In effect this means that +damage will usually result in a higher DPS increase than +crit (especially considering that Blizz values +damage lower than +crit rate, see Formulas:Item Values, spell damage is at 0.85 and crit rate at 1). Spell crit rating is expensive, but the "price" for crit rating decreases as the amount of +damage increases.

Examples (assuming a caster with 320 DPS from his spells prior to adding +damage):

+damage	base DPS	crit %	total DPS	increase
500	462.86	10%	509.14
501	463.14	10%	509.46	0.32
500	462.86	10.048%	509.37	0.23
1000	605.7	10%	666.29
1001	606	10%	666.6	0.31
1000	605.7	10.048%	666.56	0.27
1500	748.57	25%	935.71
1501	748.86	25%	936.07	0.36
1500	748.57	25.048%	936.07	0.36
2000	891.43	25%	1114.29
2001	891.71	25%	1114.64	0.35
2000	891.43	25.048%	1114.71	0.42

The first two groups show that even at +1000 damage and with a rather low critrate, +damage is still better than + crit rating, although the difference is smaller than at +500 damage. Break-even (at 10% crit) would occur at 660 base DPS, which would mean +1190 damage. So while levelling or still wearing blue/green gear, crit rating should not be a sought-after stat (if interested in a high average DPS output).

As shown in the lower two groups, +1500 damage is just enough to compensate a spell crit rate of 25% (the exact bep would be at +1505 damage, but this doesn't really matter). With even more +damage gear, increasing crit rating will be better than further +damage. At high levels with real endgame gear, crit rate is a much more interesting stat (again, strictly considering DPS only).

If we consider that Crat is 17% more expensive than Sdmg we get that the break even point is ~700 and not 600 and would show that you will mostly never want to go for crit heavy gear unless you have over 1k spelldamage andno critrating wich will never happen.

STR vs AGI

When considering the effects of str and agi on pure white DPS, Str increases DPS by a linear amount (1 Str yielding about .14 DPS), while Agi increases the chance to crit (and thus DPS) by a factor. In practise this means that depending on the current damage output, there's an equilibrium point at which the DPS increase from Agi is higher than the increase from Str.

^The above statement is wrong, strength yields ~0.14*critchance in dps, while agi gives agi*whitedps/100*agility needed per crit. Therefore this whole article is wrong since strength scales with agility damage just as well as agility scales with strength damage. The equilibrium at level 60 were 20 agi = 1 crit were one such agility point is better than one strength is extremely high. If we take a person with 15% crit, then he gets 0.16 dps per strength and 0.05% dps per agility, and as such the level 60 guy would need 320white dps before agility is as good as strength, and after that he needs to get roghly 2 agility per strength to keep the ultimate dps progression

In summary, it is rather safe to assume that endgame DPS builds should always strive for high AGI scores, whereas tanks should prefer STR. While levelling, STR is also usually better than AGI, because the equilibrium point is at a rather high value.

Strength

• Hunters/Rogues gain 1AP per str (= approx. 0.07 DPS per Str).
• All other classes gain 2AP per str (= about 0.14 DPS per Str).

Note that this is strictly melee attack power; the calculations for ranged attack power (RAP) are different. Also note that this is base "white" dps, and does not consider changes to other abilities.

Value of Agility Depending on level and class, agility increases white DPS by increasing the chance to critically hit. Additionally,

• Rogues/Hunters gain 1AP or .07 DPS per AGI.

Equilibrium Point

At this DPS point, the DPS gained by 1 STR and 1 AGI are equal. Past this point 1 AGI will always yield more DPS.

The formula to find the equilibrium point is:

DpsPerStr = CritPerAgi * X + DpsPerAgi

where

• X is the equilibrium point in DPS.
• DpsPerStr = .075 for Rogues/melee Hunters and .15 for all other classes.
• CritPerAgi = Critical Hit percentage in decimal form gained by 1 AGI point, changes based on level and class, explanation below.
• DpsPerAgi = .075 for Rogues/Hunters/Cat druids, 0 for other classes
• These constants are subject to alteration by talents. (such as Heart of the Wild)

*Because DpsPerStr and DpsPerAgi are equal for rogues and hunters, the equilibrium point is zero. There is never a point where a rogue or hunter should take a point of STR over a point of AGI.

The Above is true, but if you replace strength with attack power you get exactly the same formula. Just do it attackpower vs agility to get the same results, since 2 attackpower costs as 1 strength.

For the rest of us. Consider a level 27 NE druid (not in cat form).

DpsPerStr = .15

CritPerAgi = .001 (that is, 1 agi = 0.1% crit chance)

DpsPerAgi = 0

.15 = .001(x) + 0

x = 150

Until the shown DPS (what is shown when you hover your mouse over your damage display in the character menu) is equal to 150 it is MORE beneficial from a white DPS standpoint to put 1 point into STR than it is to put one point into AGI. After the equilibrium it is always better to put points into AGI.

Now consider for a moment that same druid in cat form.

DpsPerStr = .15

CritPerAgi = .001 (that is, 1 agi = 0.1% crit chance)

DpsPerAgi = .075

.15 = .001(x) + .075

.075 = .001(x)

x = 75

Again, remember that these constants are subject to alteration by talents.

Calculating Critical Hit per AGI

By de-equipping an item with +AGI (don't use a weapon) we can determine CritPerAgi.

• CritPerAgi = Change in crit percent / change in agility

Steps

1. Hover your mouse over your AGI and write down the percentage, we will call it Y for now.
2. Remove a piece of equipment with some AGI on it (not your weapon to keep it easy).
3. Hover your mouse over your AGI and write down the percentage again, we will it Z.
4. Y - Z = Change in crit percent.
5. Divide by the number of AGI on the equipment you removed = critical hit percentage per AGI.
6. Divide by 100 to determine CritPerAgi

Example:

I hover AGI and have a 7.27 crit percentage, remove a 4 AGI item and I have a 6.87 crit percentage.

7.27 - 6.87 = .4

.4 / 4 AGI removed = .1 crit percentage per AGI, or a CritPerAgi of .001.

Note: It is important to hover over AGI to determine your current critical hit percentage because the critical hit percentage shown in your character window is a the sum of many factors including current weapon skill, + crit items etc. If you do the calculations based on the change in that number you will be off in your math, you must do the calculations based purely off the change in the AGI derived critical hit percentage. In the prior paragraph where we determined Current DPS, you will want to use the shown critical hit percentage to determine current DPS because you are interested in the current amount of damage you do.

Determining Current DPS

By determining our current DPS we can figure out how close we are to reaching that equilibrium point and therefore help to guide is in future equipment upgrades.

• current white DPS is equal to Shown DPS * (1 + critical hit percentage).

Therefore on the druid above.

Shown DPS is 24.1 and critical hit in caster form is 6.14%.

White DPS = 24.1 * (1.0614) = 25.57974.

Plugging it into the equilibrium equation we deduce that at this point it is without question more beneficial to increase STR than AGI when evaluating based on DPS.

Other considerations

Str and Agi both can also help to reduce damage taken. Agi increases the chances to dodge, Str increases the amounts blocked with a shield. Additionally, there are talents like [Flurry] which can proc off critical hits, and complicate these calculations further.

See the discussions page for further insights.