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Discussion on fires per minute + spreadsheet I made

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4,255 battles


Recently I created a spreadsheet that lists all tier 8-10 destroyers and cruisers and their respective statistics for fires per minute, that I would like to share to the forum community as a potentially useful tool.

In the past I often wondered questions such as whether I should take Demolition Expert or Basic Firing Training on a gunboat destroyer to be able to set more fires. To answer this question I came up with the following equation: RPM x (1 - (1 - fire chance) ^ number of guns). Mathematical explanation in the spoiler box.


Suppose each shell a ship fires has a chance of igniting a fire F, which would be a decimal value such as 0.08 or 0.12. Suppose this same ship has a number of guns G. We first determine the chance of not inflicting a fire per shell, which would be 1 - F. Because the ship has G guns, we compute (1 - F) ^ G to compute the probability that none of the shells landing on target ignite a fire. We are interested in the probability of setting at least one fire, so we again subtract this value from 1 to yield the expression 1 - (1 - F) ^ G; we can then multiply this by the ship's RPM to yield an expression for fires per minute.

There are some gameplay intricacies and limitations that influenced this formula. The following information can be found on the World of Warships wiki page on Fires.  Firstly, we know that ships are compartmentalized into four distinct fire zones. Realistically, in battle, factors such as shell dispersion and HE shell explosion radii allow the possibility of a single salvo to inflict multiple fires on a target. However, because I'm not smart enough to think of a way to include these kinds of factors in this relatively simple equation, I am treating all of the shells in the salvo (all G shells, if you will) as a single projectile, that lands on only one fire zone. This is unrealistic in the context of the game, but to attempt to include those factors would be far too complex. We are also, of course, assuming that all of the shells land on target, and we ignore shell flight travel time, which is again unrealistic. These are all compromises that I hope can be ignored for the sake of using this equation as a metric of purely outgoing fires per minute potential.

Let's make a sample calculation. Take the Des Moines, tier X American cruiser, which has a rate of fire of 10.91, nine guns, and a base fire chance of 14%, or 0.14. In the equation, we get 10.91 * (1 - (1 - 0.14) ^ 9) = 8.103 fires per minute.

However, this doesn't include other influencing variables. What if you have the Demolition Expert skill? What if your target's captain has the Fire Prevention skill? What if you are using a destroyer and have the Basic Firing Training skill? As you can imagine, the computation then becomes very complex. And don't forget ships have native tier-dependent base fire resistance coefficients

So I made a spreadsheet on Google Sheets that will do all the work for you. Here's a link, where you can copy my sheet to your own Google Drive. I have checkboxes that you are free to check or uncheck, that will apply some effect (BFT, DE, etc.) to the ship of your choice, and you can then see the change in your fires/minute calculation.

Full list of features as of posting this forum topic:

  • List of all tier 8-10 destroyers and cruisers, including Premium ships and test ships - all data taken from wowsft.com
  • HE shell penetration calculations, including special cases such as IJN 100mm destroyers, etc.
  • Include the following factors that influence rate of fire, chance of igniting fire, or HE penetration:
    • Equipment (including Legendary modules)
    • Captain skills
    • Signal flags
    • Target's fire prevention measures (Fire Prevention skill, etc.)
  • Color coding and conditional formatting for ease of viewership
  • Easy-to-use user interface with checkboxes
  • Ongoing support and updates

As this is an ongoing endeavor I'll do my best to keep it updated. Unfortunately, because Google Sheets treats marking checkboxes as editing the spreadsheet, I can only share this sheet by forcing users to make a copy of it, meaning if I change my sheet, updates will not propagate to copies of the sheet. This means users will have to periodically make new copies of the sheet.

Anyways, any feedback, questions, requests, etc. are welcome. I discuss and post update/change notifications to the sheet in the [O7] Discord server so join us if you would like.



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Clan Supertest Coordinator
5,295 posts
8,554 battles

I've always just taken the simple/crude approach of comparing aggregate fire chance to establish a rough benchmark in which to compare ships.  


(Rounds Per Minute * Number of Barrels * Fire Chance)


It won't tell you anything meaningful as far as gameplay is concerned, but it does server as a crude way to compare ships and it's incredibly easy to calculate using a simple calculator/phone.   


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785 posts
12,338 battles

Very interesting, thanks for your work.

Seems to confirm some contentious opinions about certain nations being OP, relative to others.

There are 10 ships that start more than 5 fires per minute. Of these, 5 (half of them) come from one nation. This nation also has the number one spot, for the biggest fire starter of them all.

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