# How is damage calculated?

Most weapons of the same level and rarity have pretty identical attack stats (at least in shops anyway), but the actual damage they deal is drastically different. Example: a 100 attack hand cannon deals a lot more damage than a 100 attack auto rifle.

Is there a formula or way to tell how much damage I can actually expect to be dealing with this gun when it has that attack?

• Was there a difference in impact level between the two and were you testing this on the same level enemy with both guns?
– Zero
Sep 11, 2014 at 14:32
• No calculations, but here is a good reference for weapon stats. Sep 11, 2014 at 14:36
• @ZeroStack Impact stat has nothing to do with damage as far as I know. It varies between guns even in the same family. Impact stat is chance to stagger. I had 2 sniper rifles that did the same damage even though their impact stats were very different. Sep 11, 2014 at 14:36
• I thought impact affected the amount of damage you did to enemies of low level, where it caps the total damage you can do to them. I do know that the crit modifier is different on various weapons. And the sniper and hand cannons make the crit zone hitbox larger, as well as having a high crit multiplier. Hand cannons are now actually quite good, surprisingly enough.
– Eben
Sep 11, 2014 at 18:13
• I thought (emphasis on thought) that impact was damage by each round, and then you have rate of fire, and that the damage value on the weapon was a "dps" type of calculation, which meant that a low-damage-per-bullt with a high-rate-of-fire could do the same dps as a weapon with the two values reversed. Sep 12, 2014 at 10:02

So far my data points to this being the right explanation: Impact is a measure of how much to scale the Attack of the weapon by, to determine a per-bullet damage. If you make a plot betwen Impact and bullet damage in weapons with the same Attack (sidenote: all weapons of the same level, rarity and weapon slot have the same Attack) you'll see a correlation. I don't know the exact scaling factors and numbers involved, or whether this changes as you go up towards legendaries/exotics as my data is mostly from the most consistent baseline source of weapons I have (white primary engrams from Cryptarch, which give lvl 15 weapons). I also only own a single legendary and no exotic weapons.

This means that if you're comparing Attack directly you might as well be comparing levels. Impact will give you a rough idea of how large the single-shot damage will be relative to other weapons with the same Attack, but if you're comparing a lower Attack weapon with one with a higher Attack, you'll have to do some quick headmath to determine if the weapon will do the right kind of damage for your usage pattern, based on impact difference and rate of fire. In general at this point it's better to just testfire the weapon.

The data I refer to is available in this google spreadsheet

I can only offer educated guesses on my experience while playing the game, and short of a developer jumping on here an answering flat out I doubt we will ever have a definitive answer.

I believe the damage value is the exact same representation that you would see on weapons in Diablo 3, it is an aggregated value based on the stats of the weapon. In the case of destiny it would be a calculation of damage per round then normalized/averaged over a defined time period in this case likely a period of 1 sec.

I am firm in this belief because it is the only explanation I can come up with for the differences you note between a hand cannon and an auto rifle.

TL;DR; The damage value is Damage per second and not Damage per shot.

Impact stat is how much damage you deal per shot. The higher the impact, the more damage you deal each time a bullet connects. High impact weapons also tend to have low rates of fire.

The attack stat is a multiplier that affects how much damage you deal to different level enemies. It's fairly complicated. (It helps to think of it as a kind of armour pierce)

Basically, in PvP, ignore the attack stat completely, unless you're in a mode that has level advantage enabled.

For PvE, just try out weapons. High attack weapons deal more damage to higher level enemies than low attack weapons, but you just need to find a balance.

• See my comment in the question about the Trajan-C Sniper rifle, it has very low impact, but still deals a ton of damage. Impact being the determining factor in damage doesn't make much sense after seeing that. Sep 18, 2014 at 12:01
• I was just going off the information in the official guide. Like I said, it's complicated :( Sep 18, 2014 at 18:08
• Yeah, don't worry about it. This might be correct, but I'd like to see hard numbers/formula or some sort of proof confirming it to mark the answer as correct let alone award bounty. Sep 18, 2014 at 18:21
• Which official guide? Sep 24, 2014 at 11:25

Impact does determine dmg per shot.

The rate of fire/impact stats of weapons can be used to compare similair weapons of the same type. e.g. a lvl 20 sniper with high impact will deal more dmg per shot than a lvl 20 sniper with lower impact, but also fire slower.

Also, don't try to compare the impact and rate of fire stats of different weapon types. (A pulse rifle can have an apparent higher impact than a sniper rifle, but will not deal more dmg per shot than the sniper. Same for rate of fire. These values are just for comparing sniper to sniper, pulse rifle to pulse rifle, etc...)

Not sure how the attack value works but I guess higher attack just means more dmg to pve enemies.

• I am happy to believe that rate of Fire influences damage since a constant DPS for a given damage rating would make sense which would mean that a faster rate of fire would be less damage per shot. You seem to be additionally saying that anything with a high impact has a lower rate of fire though. I can't check at the moment but are you saying that two guns with the same damage rating and same rate of fire would have different damage per shot if the impact rating is different? Oct 27, 2014 at 9:53

I doubt impact is the damage per shot. My rare sniper level 18 with 219 attack has half the impact as my level 16 rare pulse rifle with 215 attack. Also it would mean that rocket launchers don't do any damage since they don't have an impact stat.

• Also the "Upgrade damage" mods increase attack rather than impact. Sep 23, 2014 at 0:09
• Could you provide some "calculation"? the question is asking about the math itself. Sep 23, 2014 at 1:04
• Nobody knows how to calculate this except Bungie. They aren't telling. Even the official guides, like the one from Prima Guides (which appears to be the Brady guide) doesn't say exactly how all these numbers interact. It does say that higher impact means more damage if the attack numbers are comparable, but it does not show any formula. Either forego the need for actual hard math, or we'll have to experiment a lot to see if we can see a pattern. Sep 24, 2014 at 11:37