I've read the answers and comments from this question.

I know:

  • encounters get more difficult the longer you stay out.
  • loot gets better the longer you stay out.
  • there is a special encounter at 2.5 days, with a chance for ledgendary gear.
  • you can only send 25 stimpaks/rad aways with any one dweller
  • a dweller who collects 100 items (weapons/armour) will return to the vault on his/her own.

Is there a point where it is more valuable to return (and take another run at the National Guard Depot) instead of keep going until your supplies run out or your inventory fills?

Test case: I have an explorer who is over 3 days out, but still has 13 stimpaks.

1 Answer 1


The following is largely taken as is from Google Docs "Fallout Shelter Efficiency Data"

I do not know the authours or contributors of this document in any way.

The in-game guide states "The further out they go, the better rewards they'll find, but the harder the encounters will become"

This infers that as the probability of loot being rare/legendary increasing with time.

A regular loot event occurs every 60 minutes for all dwellers exploring in the wastelands. This is confirmed to have a chance to acquire rare and legendary gear. Only Legendary weapons have been gained this way, not armour.

Rare drops after 25 days in the wastes are confirmed to be 100%.

  • Chance at Rare = Duration in Minutes / 36,000
  • Chance at Legendary = Duration in Minutes / 360,000
    • Chance at Legendary may be capped at one legendary per expedition.

Also, when your dweller reaches 60 hours (plus or minus 15 minutes), they will encounter the National Guard Depot. This will always happen. However, you do not always gain the legendary gear. It is suggested that this is based on a Perception test, but this is not confirmed.

In conclusion:

If you are looking for Legendary gear, stay out there as long as possible, but consider coming back as soon as you have one.

If you are are okay with only 1 piece of Legendary equipment per expedition, stay out as long as possible and collect as much better-than-common gear as possible. And if you find that you can indeed gain more than 1 Legendary gear, then by all means share that information.

  • My gawd, 25 days? that means it'll take 12 days for him to return...
    – Nelson
    Commented Jan 15, 2016 at 17:41
  • @Nelson unless they have either a Husky or Sphynx (they reduce the wasteland return time) Commented Jan 15, 2016 at 18:05
  • @Nelson, also time-glitching was used to confirm this... so maybe they didn't need to wait that long for them to come back. Commented Jan 25, 2016 at 20:39
  • The base return time is half the outbound trip time. If they went out for 25 days, their base return trip will be 12.5 days. I don't know how you can have someone go out for 25 days though. A max stat dweller with bonus E (no rad damage) can only last at most 10ish days with 25 Stims.
    – Nelson
    Commented Jan 26, 2016 at 5:50
  • @Nelson actually you would have a hard time keeping them out even 10 days due to the max number of items they can carry (which is 100). Commented Jan 26, 2016 at 18:36

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