Since these sorts of questions are asked several times a week, I'm posting this INFO post... hopefully it either gets stickied, or the relevant information is placed into a sticky :)

People often make the mistake of thinking that effects like Slice and Dice or Flurry are improperly increasing your attack speed, but the fact is they simply are not understanding the math.

The formula to remember is:

NEW_SPEED = OLD_SPEED / (1 + HASTE_PERCENT)

(where a 30% haste is represented as 0.30, obviously)

While these are technically the same for both melee/ranged, and spells, I'll break it down, anyway:

For melee/ranged:

(Flurry, Slice and Dice, Blade Flurry, Heroism/Bloodlust, Rapid Fire, Serpent's Swiftness, Quick Shots, etc...)

Haste effects grant an increase in ATTACK SPEED, which is the inverse of your swing (shot) timer.

Some examples:

2.0s/swing @ 30% haste:
2.0 / (1 + 0.30) = 1.538sec/swing

and

3.6s/swing @ 20% haste:
3.6 / (1 + 0.20) = 3.000sec/seing


If you want to look at it another way (some people understand this more easily), let's convert swing timer into attacks per timeframe (1min, in this example):

2.0sec / swing = 30 swing/min
30 swing/min * 1.3 = 39 swing/min
60 seconds/min / 39 swing/min = 1.538 seconds / swing

and

3.6sec / swing = 16.666 swing/min
16.666 swing/min * 1.2 = 20 swings/min
60 sec/min / 20 wing/min = 3.0 seconds/swing




For spells:

The easiest way to think of spell haste is to consider it in terms of how may spells can you cast in a given timeframe. I usually use one minute, to make it easy.

As an example:

Assume a 5 second cast time on a spell.

This means you can cast 60/5 = 12 spells in one minute (assuming no lag :P ).

If you can cast 50% faster, this means you'll cast 50% more spells in the
same timeframe (follow so far?).

Thus:

12 * 1.5 = 18

You'd be able to cast 18 spells in 60 seconds.

This means your spell cast length is:

60/18 = 3.333 seconds

You'll get the same number using the above formula:

5.0 / (1 + 0.50) = 3.333 sec


Hope that makes sense to everyone.

-T

[ Post edited by Duman ]

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70 Paladin, 70 Rogue, 70 Priest, 61 Druid, etc...

Thanks Duman, I've added a short explanation of this to the "Issues that are not bugs" sticky.