When does the critical hit calculation take place?

Does a critical hit guarantee that my shot will strike its target, or is a critical hit chance only calculated if a shot hits the target in the first place?

  • The fact the cinematic view kicks before the shot implies it knows you kill the enemy before the shot takes place. So it must calculate damage before then.
    – Shykin
    Commented Oct 12, 2012 at 19:14

1 Answer 1


Critical hits do extra damage; they do not guarantee hits. What I believe is happening is:

  1. Xcom rolls a hit (using the next randomly generated number)

  2. Xcom rolls to see if you hit some cover or some other enemy(??), if you missed.

  3. Checks critical chance if it's applicable (Cyberdisc's in disc form cannot be critted, there may be other scenarios where Crits do not apply). I have no idea if you can crit cover but I sort of doubt it.

  4. Calculates damage if and only if there is a hit, and then calculates it differently on a crit. If you miss and hit cover, it might also calculate damage.

So the possibly sequences would be:


Miss/??/?? affect some cover somewhere (or hit annother alien? Such things have been reported; one would expect damage to be rolled there)

Hit/non-crit/normal damage

Hit/Crit/crit damage

Once it calculates each of these things as needed, it shows you the results in game.

I know cover can be damaged/destroyed, but we need more data on what precisely is going on. Does cover have HP and are you taking away from that pool? Is it just reduced a step or possibly fully? I don't know. I have never observed a stray shot hit another enemy but that is entirely anecdotal and should be taken with a grain of salt. There appears to be no friendly fire on "normal" attacks (i.e. not using grenades or rockets). Observations in the comments suggest that the criticals are handled via a second roll; that is, you do have to roll to hit and then roll to see if you crit.

See Are Hit Chances Predetermined commentary on Xcom: Enemy Unknown's generation of random numbers.

  • according to both me and saintwacko's observations here its definitely possible for stray shots to hit enemies, be it from you or the enemy itself.
    – l I
    Commented Oct 12, 2012 at 19:58
  • @yk I have never seen it. Further, I have seen my shots stray and hit other enemies not in cover, and no damage was done. I don't say that to call you a liar or anything; I'm very curious to know what is going on. As I said elsewhere, sometimes I think it's really shots hitting cover but it looks goofy. But I just observed it on a "stray" enemy out in the open, no damage (from a plasma rifle).
    – peacedog
    Commented Oct 12, 2012 at 21:51
  • I think the biggest question that I don't think your answer makes clear is if it is a one or two roll crit system. ie if you have 50% crit and 75% hit does that mean that on a roll of 1-100 that 1-50 is a crit, 51-75 is a normal hit and 76-100 is a miss or does it roll and say 1-75 is a hit and then if a hit roll again with 1-50 being a crit. I think it is the first system but I've not checked (easy way to check is for times when crit >=hit you should never get a non-crit on a one roll system.
    – Chris
    Commented Oct 15, 2012 at 15:25
  • @Chris - I have not seen any evidence to suggest it's one or the other. My answer assumes it's a two roll system; I doubt we'll ever know the truth.
    – peacedog
    Commented Oct 15, 2012 at 16:19
  • 2
    Last night I proved to my own satisfaction that it is a two roll system with a 70% chance of hit and crit I got a standard hit which would not be possible in the one roll system. It does mean crit is not quite as good as I thought it was sadly. :(
    – Chris
    Commented Oct 17, 2012 at 8:26

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