What is the sneak detection equation in Fallout: New Vegas?

What factors (other than perks and hiding behind things) determines if you are detected while sneaking?

I have read a lot of conflicting information about if/how these things affect sneak detection:

  • armor weight
  • inventory weight
  • weapon weight

Is there a definitive source of information to solve this problem?

1 Answer 1


There are many factors involved in stealth calculation :

Sneak Skill, obviously. This can be improved temporarily or permanently by perks and items.

Enemy Perception stat : it is worth noting that a crippled head cause a -4 modifier

Light level : less light = more difficult to see. Be careful for your Pip-Boy light.

Movement : this includes looking around. The more you move, the more you are likely to be detected.

Contact : usurprisingly, being in direct physical contact with any target makes it aware of your position

Sound : you emit sound in two ways :

  • Most weapons are noisy. Some are silenced : they don't emit sound when you use them ; that includes melee weapons and grenades (throwing is silent). Being attacked will always cause a NPC to enter [CAUTION] mode.
  • Moving emits sound, which scales with your equipped weight ; this only includes your weapon if it is drawn. The perk "Silent Runner" negates this entirely.


Line of sight : if you cannot be seen, you can only be heard.

  • The "Silent Running" perk says it only makes running less detectable while sneaking. It doesn't mention anything about equipped weight. fallout.wikia.com/wiki/Silent_Running Commented Aug 6, 2015 at 16:19
  • 1
    It does so by completely eliminating the noise you emit by moving, which is dependent on the equipped weight.
    – Ealhad
    Commented Aug 6, 2015 at 16:21
  • Ah, I guess that is the information I needed. Sneak seems pretty useless in New Vegas without Silent Running then. Thanks. Commented Aug 6, 2015 at 17:06
  • @theJollySin Well, just walk =D
    – Ealhad
    Commented Aug 6, 2015 at 17:09

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