I recently started playing Fallout Shelter, but I go hours without opening the game and collecting resources. When I go back to the game it looks like a little bit of my existing resources have been used, but not by much. However, if I leave the game open, and watch my vault dwellers I can see my resources being used up at a much faster rate. I'm curious if this is explained anywhere. I'm also curious what the rate of resource consumption is while the game is idle vs the rate of consumption while I'm actively playing it.

2 Answers 2


The game has 2 different running in background behaviours:

  • The game's wiki specifies that the resources will be consumed only for a little while after the game is no longer in use (game sent to background, phone not used etc). This is due to the fact that the resources require a lot of management and you would have to check/play the game every few minutes, half an hour at most, before your dwellers would start dying, get irradiated, etc
  • Other activities that require a long time will still be in play (or generated once you open the game again, based on how long actually took since you last stopped playing - in normal hours) ... these activities are: wasteland exploration and returning, training, pregnancy, baby growing up, radio and creating resources
  • You will also never be attacked by raiders, deathclaw or molerats while the game is on background.

As an example: A baby requires 3 hours in order to grow up and become an adult. When you open the game again, the game will check if 3 hours have passed since the baby was born to determine whether to make that baby an adult.

Warning: Players tried to fool the game by changing the timer, clock... be aware that this can cause lots of bugs, malfunctions, freezes, crashes etc

TL/DR: Yes, resources will be consumed only when you play the game or for a short while after you stop playing the game.

  • So, the short answer is Yes. Aug 20, 2015 at 14:25
  • Interesting, I didn't realize all consumption of resources stopped after a certain point once the game is not active. I thought the consumption of resources was still happening, but at a much slower rate. Do you know how long the game has to be inactive for resources to stop being consumed?
    – onewho
    Aug 20, 2015 at 14:36
  • The game's help guide actually says: short time :) So don't really know but in my experience I think it's less than a minute.
    – spauny
    Aug 20, 2015 at 14:43
  • You can, in fact, get attacked while "idle".
    – user106385
    Aug 21, 2015 at 2:16
  • @Timelord64 - It never happened to me and I was reading about it... there are a very few people complaining about this while the majority says it can't happen. So this may very well be a bug where the game still acts as active...
    – spauny
    Aug 21, 2015 at 8:13

how the game works is if you're making more food/water/power than you're consuming then when you turn the game off it will only consume until all rooms are ready to collect, so that's why you lose more food when playing

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