In Fallout Shelter you're able to rush the product of a resource. According to the game, it is influenced by the luck of the people assigned to the room and whether or not you have recently rushed the room. However, as the incident rate goes down, so do the rewards for rushing. What are the underlying mechanics? I would like to maximize my rush success chances, and the possible payoffs.

  • You answered your own question in the question....just an FYI
    – Dupree3
    Jun 19, 2015 at 15:14
  • @Dupree3 The question is asking what exactly affects this. "it is influenced by the luck of the people in the room" is hardly exact.
    – Unionhawk
    Jun 19, 2015 at 15:18
  • @Unionhawk Sounds pretty self explanatory to me, answered his own question
    – Dupree3
    Jun 30, 2015 at 15:29
  • No, @Dupree3, I didn't. I'm asking for far more detail than just "these two factors have an affect". I'm looking for mechanics and any other possible options.
    – two bugs
    Jun 30, 2015 at 15:37

5 Answers 5


There are mainly 3 factors which seems to take effect on the rush accident rate:

  1. The summed amount of stats. For example the Reactor: I have one reactor with 3 People inside it, all have around S:3. It has a higher accident rate than a room with just one Person in it with S:10, but the same accident rate as a Person with S:9. This leads me to the conclusion, that the right stat in sum(!) will take effect on the accident rate.
  2. Beside the correct stat for a room (S:Reactor, P:Water, A:Dinner,...) the L factor takes effect. Just like in the real fallout games too. L will always improve percentage values. In this case I have a room with same needed stats (S:9 for example), one with L:2 one with L:8 (maybe due to more people in it). The room with higher L has a accident rate of 14 as the other room has a accident rate of 19 percent.
  3. The time! If you rush a room too often in a too short range of time, the accident rate will grow. On rooms with a good stuffing (high stats which are needed + luck) your able to rush 1-3 times before it will get to a "critical" accident rate of 30%. After a few collections it's back to its original accident rate of 10%.

Hopefully this will help you.

  • Do you have any evidence or a source for this? In my experience the SPECIAL values of the assigned people seems to only affect the time for the room to generate resources.
    – two bugs
    Jun 17, 2015 at 13:07
  • Ah your right. Sorry. I thought I've seen that those values also downed. Maybe it was some other dependency. Maybe this was a correlation of other values? As I've changed the person too.
    – Ionic
    Jun 17, 2015 at 13:10
  • Hi, I've updated the whole answer. I have checked some of the stats over time and that's my observation of it.
    – Ionic
    Jun 21, 2015 at 10:33
  • 2
    @Ionic Can you double-check whether it's just time that reduces accident rate, or is it actually the collection of resources? James suggested it's resource collection, and I've witnessed the same. Test: 1.) Check accident rate immediately after resource collection. 2.) Do nothing in that room until ~20 seconds before next resource drop. 3.) Check accident rate again. 4.) Collect resources. 4.) Check accident rate again.
    – Iszi
    Jun 24, 2015 at 19:15
  • Yes it's seems to be the collection which counts. :-) I've changed the answer.
    – Ionic
    Jun 24, 2015 at 19:41

I failed a 3 percent rush this morning in my water treatment plant (size 1) with two dwellers. Dweller 1 had 8 (+5) perception and dweller 2 had 9 (+2) perception. In addition dweller 1 had 3 luck and dweller 2 had 9 (+1) luck. I succeeded at rushing at 13 percent right after, and then rushed again at 23 percent and failed. I don't undertand what's going on behind the scenes at all. I also tested the probability of passing at rush at high percentages. I rushed a room with 6 dwellers (not sure of the exact stats) again and again at 80 percent and 90 percent (after it goes up to 90 and you fail, it goes down to 80 immediately). I rushed maybe 50 times and never succeeded one time. The probability of failing seems much higher than passing regardless of percentages.


Failure rate = 40 - 2 * (Average room Luck + Average room Skill) + 10 for each successive rush (up to +50)

Use one maxed dweller in a tripple lvl 3 room and you always complete the first rush.

Average room luck also increases chance to get +200 caps when picking up reasources.

Source: https://docs.google.com/spreadsheets/d/1Nai09D_aM2syl3iPP5hkveDcOUwhsoUDR6s1lwC0e8c/htmlview?pli=1&sle=true#

  • That's odd. Did they change the formula? It was definitely the SUM of the skills before, not the average.
    – DCShannon
    May 11, 2016 at 23:45
  • The new 1.5 patch may have changed the formula to always be at least 10%
    – SkyHiRider
    May 13, 2016 at 11:55

I am currently gathering intel on this as well and here is what I have seen from my own observations

  • The incident rate seems to start at around 31% (this is with 2-4 people in the room with ok stats)
  • It increases every time you do a rush whether you fail or succeed by about 10%
  • The chance of failure also seems to decrease again once you successfully collect a resource from the room (with out having rushed it ofcourse).

I have not had good luck finding lucky people to see how they impact the results, not a large variation in stats as I have just started and do not have the stat raising rooms as of yet for further exploration of this.

  • I have some highly special dwellers whose skills reduce the rate as low as 12%.
    – Shon
    Jun 20, 2015 at 12:31

The Vault Dweller's luck and how much time has elapsed since the last rush, although I don't know the exact numbers.

  • Can you elaborate?
    – Schism
    Jun 17, 2015 at 5:11
  • From my experience, there are two types of probabilities, the shown values and the ACTUAL success rate. The shown values are determined by the number of people inside, (haven't tested whether high/low level changes it) Luck affects how it actually plays out (if you have a room with low luck people it tends to start failing at ~40%, but if you have a few lucky people it'll only start failing at ~70%)
    – Jonny Lin
    Jun 18, 2015 at 4:31

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