D&D 4E The math behind power attack and why it needs to be redone in 4e

Here is some basic math that simply presents the Power Attack issues:

Lets assume we have a character with a to hit roll modifier of +15 (all bonuses included)

Lets say our monster has an AC of 26 (giving our hero a 50% chance to hit)

Our hero has power attack and deals 1d8+3 damage. The average damage is 7.5.

Because the hero has a 50% chance to hit, they will deal 3.75 damage per attack.

Here is the effect that power attack has:

+hit %hit av. damage
15 50% 3.75
14 45% 3.825
13 40% 3.8
12 35% 3.675
11 30% 3.45
10 25% 3.125
9 20% 2.7
8 15% 2.175
7 10% 1.65
6 5% 0.875

This shows you exactly how power attack works. As the hero takes greater penalties to hit, and thus adds to damage, they actually do less damage over time. This at the cost of a feat. Power attack only benefits you if you have excessive BAB or within a small amount used +1 or +2. Even then, the effect is negligible.

If you look at power attack with monsters with a much lower AC (say 17), and thus higher chance to hit, it looks like this as you use it:

+hit %hit av. damage
15 95% 7.125
14 90% 7.65
13 85% 8.075
12 80% 8.4
11 75% 8.625
10 70% 8.75
9 65% 8.775
8 60% 8.7
7 55% 9.075
6 50% 8.75

Ironically, power attack fluctuates up and down as you go down the chart. But overall, when you have a high base attack bonus, it gives you about +1 damage extra, all for a feat.

The ONLY exception is when your to BAB is far higher then needed. So much so that you can take all of the excessive, still hit on anything but a 1 and then add that difference to your damage. That is the ONLY place power attack really does anything at all.

Now, here is where all the arguments come in. But for a starting feat, that a 1st level character can have and doesn't get ANY benefit from at all. That it takes using with tables like these to understand and I won't really break it until high level and then once I do it can add gross amounts of damage to monsters that are already easy to hit.

Power attack doesn't work like it advertises. It confuses new players and lies to veteran players. It is pure luck if you get it to work for you, and your missing more than you realize, likely only remembering when it is lucky. Power attack needs an overhaul, badly.

You left out crits.

Also, when the damage is 1d8+15, the math works out a lot better. Who attacks an AC 26 monster with a 1d8+3 attack?

oh, and it is very very common for fighters in the 7+ level range to hit with attacks much lower than 11, so that also helps.

And DR also factors in significantly

Oh yeah, and the fun of a massive hit.

BryonD said:

You left out crits.

Also, when the damage is 1d8+15, the math works out a lot better. Who attacks an AC 26 monster with a 1d8+3 attack?

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Just what I would have asked. Give the fighter a two handed weapon and all sorts of damage bonuses and the math changes quite a bit.

BryonD said:

Also, when the damage is 1d8+15, the math works out a lot better.

Click to expand...

No it doesn't, and in fact it works out worse, because the penalty for missing is so much bigger. Instead of missing out on an average of 7.5 damage for an unsuccessful attack taht dealt 1d8+3, you're missing out in an average of 18.5 damage. And when you do a lot of damage without Power Attack, you certainly don't want to do anything that increases your chance of missing.

That's the basic reason why Power Attack is extremely sub-optimal, even with the 2-for-1 two-handed power attack, except when you're virtually guaranteed to hit, have virtually no chance of hitting, or need to overcome DR.

Having said that, if Tweet's blog is any indication, Power Attack is going to be totally re-worked in 4e if it's there at all.

Increasing the damage and adding in critical hits makes power attack worse.

Lowering the "to hit" number helps though.

Power Attack is good for:
1. People who can do the math and have an idea when a creature's AC is low enough for them to benefit.
2. People who hate math and think it's always good, so they end up having fun while doing it.

"It's suboptimal but fun!" is a terrible argument in defense of a mechanic. A good mechanic is one that rewards you for doing fun things, not one that penalizes you for it!

I like what Iron Heroes does with it: You take a penalty, but get an additional bonus, like not only more damage but a chance to daze the opponent for a round.

But yeah, if you want PA to be useful, you have to max out your attack bonus like nobody's business. Again, Iron Heroes helps with the Weapon Master with a +25 BAB over 20 levels.

How about some real examples?


In my game the 14th level Barbarian attacks with a +26 when raging and usually has a +28 or so going from misc buffs. Looking in the MM at CR 13 and 14 monsters you will find that ACs are typically in the 26 -28 range (lows around 19 and highs of around 32). So the base 50% hit chance is off by approximately 50%. (and yes, a 1 is still a miss, but in the case of PA that extra point still applies because it becomes +2 damage for no cost at all). The barbarian crits on a 19 for X3.

Against AC 26 the optimum is at PA -7/+14, but the damage output is increased for any PA up to -15/+30. His BAB is not +15, so any PA he selects will increase damage.

Now assume DR5 or DR 10 and the numbers get even better.

Now, I like to mix it up and I will throw stuff with an AC of 35 at the party. But this does not slow the game down. Instead, the barbarian simply stops using PA. simple.