Welcome to Jester's Trek.
I'm your host, Jester. I've been an EVE Online player for about six years. One of my four mains is Ripard Teg, pictured at left. Sadly, I've succumbed to "bittervet" disease, but I'm wandering the New Eden landscape (and from time to time, the MMO landscape) in search of a cure.
You can follow along, if you want...

Sunday, November 24, 2013

Sunday definition: Stacking penalties

And now, an EVE term definition for the newer EVE players.  You vets can move on to the next post.

When you fit multiple modules of the same type to your ship, the in-game information for many of these modules reports:
Penalty: Using more than one type of this module or similar modules that affect the same attribute on the ship will be penalized.
That raises the question: what are the stacking penalties for fitting multiple modules of the same or similar type? They are:
  • The first module is 100% effective;
  • the second is 86.9% effective;
  • the third is 57.1% effective;
  • the fourth is 28.2% effective;
  • the fifth is 10.6% effective; and,
  • the sixth module is 3.0% effective.
This means in practice that the first Heat Sink II fitted to a ship adds 10% damage and reduces cycle duration by 10.5%.  The fifth one adds about 1% damage and reduces cycle duration by about 1.6%. In short, it probably won't be worth your time to do it unless you're fitting the modules to an all-gank Revelation or something.

The effect on "similar types" happens when you fit several modules that all affect the same attributes of your ship. For instance, two Energized Adaptive Nano Membranes will have stacking penalties, as will the active or passive hardeners for specific types of damage that you fit to the same ship. In each case, it will be the module that is most effective at each step in the math that will be penalized the least.

To check whether a mod has this stacking penalty, check the mod description (or see the bottom of this post). But most of the time, stacking penalties apply to modules that have an additive or subtractive percentage impact either on your own ship or another ship. Modules that have an integer effect on your own or another ship usually do not have stacking penalties. For instance, Stasis Webifiers (which reduce ship speed by a percentage) have stacking penalties, but Warp Disruptors (which have reduce warp strength by an integer value) do not. Most often, stacking penalties are most often thought-of when it comes to defensive modules (notably the Adaptive Invulnerability Field and the Energized Adaptive Nano Membrane) and weapon upgrade modules (the Heat Sink, Gyrostabilizer, Magnetic Field Stabilizer, and Ballistic Control System).

Stacking penalties can sometimes have surprising results as well. For instance, the effect of five small stasis webifying drones, the Warrior SW-300, stack. So the first SW-300 reduces target speed by 5%. But the fifth one reduces target speed by only 0.53%. So while intuitively you might believe five small webifying drones would reduce target speed by 25%, in reality they reduce it by only 14%. It is therefore more effective on paper to launch a single large stasis webifying drone at a target (for a 20% reduction in speed) than five small drones with the same size and bandwidth.

Though of course the smaller drones being half again as fast might actually catch the target whereas the large one might not...

Finally, it's worth noting that there are two modules in the game that do not have stacking penalties with other similar modules: the Damage Control and the Reactive Armor Hardener. But of course you can only fit one of these per ship. But if you fit both of them, then the less effective one of these two modules will be stacking penalized!

You can read more detail on this topic including the actual :math: formula for stacking penalties and a table showing which module types are stacking penalized and which are not at this excellent article on the EVE University Wiki.

Occasionally on Sundays, I will be defining a common EVE term for those who might not have heard it.  If you have a suggestion for such a term, please drop it into the comments.


  1. "You vets can move on to the next post."

    Well, yeah, sure.... except sometimes you keep us waiting days for that next post, so we read these anyway!

  2. Does the bastion module give hull resistances? On battleclinic it shows 30% for each.
    and if so, does it stack with a damage control? Does this make hull tanking viable?

    1. You know, that's an excellent question. I just asked it in the CCP Skype channel. Will post here what I find out.

    2. The Bastion Module does indeed give hull resists, and it is not stacking penalized with the Damage Control. A Marauder with a T2 Damage Control and in bastion has 72% hull resistances. Furthermore, I am quite sure that modules without stacking penalty are not stacking penalized against each other as well.

  3. Also it's noteworthy that while modules have stacking penalties, some modules' effects stack with each other. For example damage mods, while the 2nd damage mod is stacking penalised its damage and RoF bonuses are affected by the first damage mod (or the other way round) which means that fitting the 2nd damage mod adds more overall dps to your fit than fitting the first damage mod did.

  4. Two caveats:

    While the beneficial effects of modules may be subject to stacking penalties, to the best of my knowledge, the harmful side-effects of certain modules (such as structural compromise from nanofibers, or cargohold size from overdrives) are not.

    And the stacking penalties only apply to modules coming off the same ship. IE: one ship hitting you with four sensor dampers will be subject to stacking penalties, while four ships hitting you with one sensor damper each won't (see spider drones or sensor damping rats in some missions, or a squad of Maulus or Celestis PVP ships).

    1. Yep, so far as I'm aware, both of these are correct. Nice addition, thanks!

    2. Oh, with one exception, the webbing drones I mentioned and other drones like them. Since those are all flagged as coming off a single ship, they will be stacking penalized. But NPC Spider drones (each of which is their own ship) will not.

    3. I disagree. Sensor damps DO stack on the target ship, even if they are from different pilots. Three pilots each putting one damp each on a target (with the same script) will have the same effect and same stacking penalty as one pilot with three damps on one target.

      The stacking penalty is per effect, as stated in the OP. So it is per script loaded.

    4. All modifiers go on the same stack, regardless of source. This is easy to test in-game. There is no (mechanical) difference between one ship applying three webs and three ships applying one web each. There isn't even a (mechanical) difference between an applied web and a fitted Trimark rig; their speed modifiers experience the usual stacking penalty in descending order of strength.

    5. "the harmful side-effects of certain modules (such as structural compromise from nanofibers, or cargohold size from overdrives) are not."

      Cargohold size is a bad example, there's never any stacking penalties on cargohold size, good or bad. Look at cargohold expanders, on the other hand, and look at the speed penalty as you add more, it clearly suffers from stacking penalties, which quickly disproves your theory.

  5. huh...i always thought that active and passive modules aren't considered 'similar' for stacking purposes...damn...

  6. It's worth pointing out that for modules with a large bonus, more is actually better, despite the stacking penalty. In the case of T2 damage mods, the second one actually gives a slightly higher DPS bump than the first one. The first module gives ~22% bonus to DPS. The second module gives another ~19% bonus (due to the 87% effectiveness). However, that 19% bonus is applied to the base + 22% from the first module. This works out such that the second T2 damage mod gives about a 6% larger increase in damage than the first one.

    For something with a much higher percentage boost, such as scripted sensor boosters (at 60%), the effect is much more noticeable. I believe that it's either the 4th or the 5th module is more effective than the first. It's only at the 5th or 6th module that you actually get smaller returns.

    "...the Damage Control and the Reactive Armor Hardener...But if you fit both of them, then the less effective one of these two modules will be stacking penalized!..."

    That's the first I've heard about that. But I just did a bit of checking, and it checks out. Kinda strange they'd do that though. It drops your total resists by not even 2% in the worst case.

  7. Thanks for referencing our wiki. We spend a good amount of time on it. However, some of it still needs to be further developed. If you want to help add or refine material on our wiki, please contact me. Thanks.

  8. You already mentioned that in a special case, but it's worth emphasizing: The stacking penalities are applied from best bonus to least one, if your modules give different bonuses. That is, don't worry, the game always applies them in the best way for you. For example, if you have a two T1 modules and a T2 with a better bonus, the T2 one will get the 100%.

    And it may not be obvious to everyone (wasn't to me at first), that rigs and stuff in weapons slot usually count towards the modules, too. For example, the Sisters Core Probe Launcher (high-slot), the Scan Rangefinding Array (mid-slot) and Small Gravity Capacitor Upgrade (rigs) all give a bonus to probing strength and share stacking penalities. (And yes, for the probing stuff, this is used to be different before and changed with Odyssey.)

  9. Not sure if you take requests or not, but I'd love to hear your thoughts with all the changes in the last year or so regarding Fleet Boosts. How they work, are they penalized, do the fleet boosts apply to the whole fleet, and then the wing and squad boosts stack on top? On grid versus off grid boosting, Skirmish vs information vs armor vs siege warfare.

    I'm about 30 days from flying a command ship and would love to read a blog of yours on the pros and cons of command ship pilots as fleet/wing/squad boosters.


  10. I understand how stacking works on my ship but what about multiple ships applying a remote effect (e.g. web) on another ship? Are you saying that two rapiers with two webs each are going to have the same effect on a target as one rapier with four webs?

    1. See above. All other things being equal, two webs off two ships are better than two webs off the same ship.

  11. "Though of course the smaller drones being half again as fast might actually catch the target whereas the large one might not..."

    Small drones beeing half as slow or twice as fast perhaps? ;)


Note: Only a member of this blog may post a comment.