D&D 5E How to calculate Passive Perception

redkobold · Apr 1, 2015

Passive Perception = 10 + Wisdom modifier

+5 if you have Advantage
-5 if you have Disadvantage

In the example in the free Basic Rules, +2 Proficiency Bonus is also included.

It does not say that the example character has Skill Proficiency in Perception so I am not clear if that was just unsaid or if the character's overall Proficiency Bonus should be added to Passive Perception.

The second option seems reasonable since it would make a higher level character generally more difficult to sneak up on and make them more likely to notice a trap that they stumble upon.

Thanks in advance.

MerricB · Apr 1, 2015

Passive Perception is 10 + your Wisdom (Perception) modifier.

Advantage/Disadvantage changes the score by +5/-5.

You'll find the full rules on page 175 of the PHB and page 59 of the free Basic Rules.

Cheers!

Greg Bradburn · Feb 2, 2018

Resurrecting and old thread, In the PHB it says:
O t h e r A c t i v i t i e s
Characters w ho turn their attention to other tasks as the
group travels are not focused on watching for danger.
These characters don’t contribute their passive Wisdom
(Perception) scores to the group’s chance of noticing
hidden threats. However, a character not watching for
danger can do one o f the following activities instead, or
some other activity with the DM’s permission.
Navigate.

What exactly does it mean to "contribute their passive perception scores to the group's chance of noticing hidden threats?" It almost sounds like passive perception is cumulative, adding all eligible party members scores to a total passive perception score. That sounds o.p.

When doing passive perception checks, does the DM just check against the highest passive perception score among eligible party members or is there a calculation that includes all party members that might notice the threat?

Thanks.

iserith · Feb 2, 2018

Greg Bradburn said:
What exactly does it mean to "contribute their passive perception scores to the group's chance of noticing hidden threats?" It almost sounds like passive perception is cumulative, adding all eligible party members scores to a total passive perception score. That sounds o.p.

When doing passive perception checks, does the DM just check against the highest passive perception score among eligible party members or is there a calculation that includes all party members that might notice the threat?

Thanks.

If you're trying to determine if a character notices a trap, then you check the DC to notice the trap against the passive Perception scores of the characters that are Keeping Watch and are in the position to notice the trap. PCs in the front rank of the marching order are typically the ones that notice traps in front of the party. Those behind the front rank have no chance.

If you're trying to determine if a character notices a stealthy monster, then you check the result of the monster's Dexterity (Stealth) check against the passive Perception scores of the characters that are Keeping Watch. If the result of the Dexterity (Stealth) check exceeds a character's passive Perception score, the character is surprised. As well, if a character is not Keeping Watch, perhaps because he or she is doing some other task that distracts from noticing hidden threats, then the character is automatically surprised - the passive Perception score does not apply. It is possible that some characters in a group are surprised and some aren't.

Greg Bradburn · Feb 2, 2018

iserith said:
If you're trying to determine if a character notices a trap, then you check the DC to notice the trap against the passive Perception scores of the characters that are Keeping Watch and are in the position to notice the trap. PCs in the front rank of the marching order are typically the ones that notice traps in front of the party. Those behind the front rank have no chance.

If you're trying to determine if a character notices a stealthy monster, then you check the result of the monster's Dexterity (Stealth) check against the passive Perception scores of the characters that are Keeping Watch. If the result of the Dexterity (Stealth) check exceeds a character's passive Perception score, the character is surprised. As well, if a character is not Keeping Watch, perhaps because he or she is doing some other task that distracts from noticing hidden threats, then the character is automatically surprised - the passive Perception score does not apply. It is possible that some characters in a group are surprised and some aren't.

Okay, so no passive perception is strictly individual and not cumulative. I think the wording in the phb is clumsy "contribute their passive perception scores to the group's chance " because it makes it sound like a "group check" with contributions from multiple characters.

Charlaquin · Feb 2, 2018

Greg Bradburn said:
What exactly does it mean to "contribute their passive perception scores to the group's chance of noticing hidden threats?" It almost sounds like passive perception is cumulative, adding all eligible party members scores to a total passive perception score. That sounds o.p.

It is not cumulative, no. If a character is not keeping watch, they do not have an opportunity to check their passive Wisdom (Perception) against the DC of any hidden creatures or objects they might pass, and can’t contribute their passive Wisdom (Perception) to group checks (a group check is a check where everyone in a group who is contributing makes a check individually. If at least half succeed, the group as a whole is successful, otherwise the group as a whole fails.)

Greg Bradburn said:
When doing passive perception checks, does the DM just check against the highest passive perception score among eligible party members or is there a calculation that includes all party members that might notice the threat?

Normally, each character’s passive Wisdom (Perception) is checked individually - just because you hear a twig snap doesn’t necessarily mean I hear it. A character who is not keeping watch doesn’t get the check.

iserith · Feb 2, 2018

Greg Bradburn said:
Okay, so no passive perception is strictly individual and not cumulative. I think the wording in the phb is clumsy "contribute their passive perception scores to the group's chance " because it makes it sound like a "group check" with contributions from multiple characters.

It could in theory be used in a group check, but in most situations, such as determining whether the party notices a trap while traveling or determining surprise, the checks resolve individually.

Greg Bradburn · Feb 2, 2018

(a group check is a check where everyone in a group who is contributing makes a check individually. If at least half succeed, the group as a whole is successful, otherwise the group as a whole fails.)

Ah, that's very helpful, and in that context the phb wording makes perfect sense.

Thanks.

Kevtron · Feb 4, 2018

MerricB said:
You'll find the full rules on page 175 of the PHB and page 59 of the free Basic Rules.

Looking in the PHB it looks like passive for any skill is 10 + all skill modifiers

iserith said:
If you're trying to determine if a character notices a stealthy monster, then you check the result of the monster's Dexterity (Stealth) check against the passive Perception scores of the characters that are Keeping Watch. If the result of the Dexterity (Stealth) check exceeds a character's passive Perception score, the character is surprised.

Looking at stealth vs perception: If my lvl 3 rogue (with +3 dex + proficiency + expertise) currently has +7 to stealth, is my passive stealth 17? If so... what does that mean exactly in terms of game play?

If a goblin's passive perception is 16 or less (and assuming they aren't actively looking for me) would I even need to roll? Sounds to me like I'm 'naturally' more stealthy than the goblin is 'naturally' perceptive.

edit. the more I think about this I guess it would be unfair/overpowered. Rogues get this trait at lvl 11 more or less, so having 'passive stealth' earlier would be impossible. Almost nothing has 18 + passive perception, so I'd never be detected.

iserith · Feb 4, 2018

Kevtron said:
Looking at stealth vs perception: If my lvl 3 rogue (with +3 dex + proficiency + expertise) currently has +7 to stealth, is my passive stealth 17? If so... what does that mean exactly in terms of game play?

If a goblin's passive perception is 16 or less (and assuming they aren't actively looking for me) would I even need to roll? Sounds to me like I'm 'naturally' more stealthy than the goblin is 'naturally' perceptive.

edit. the more I think about this I guess it would be unfair/overpowered. Rogues get this trait at lvl 11 more or less, so having 'passive stealth' earlier would be impossible. Almost nothing has 18 + passive perception, so I'd never be detected.

Passive checks resolve uncertainty in tasks that are performed repeatedly, so if a DM is calling for a passive Stealth check, then the character must be trying to be stealthy on an ongoing basis without interruption. I doubt this would come up very often, but it might be a way of resolving, for example, whether or not the character might be detected during extended travel through a dangerous place or the like.

D&D 5E How to calculate Passive Perception

redkobold

Explorer

MerricB

Eternal Optimist

Greg Bradburn

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iserith

Magic Wordsmith

Greg Bradburn

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Charlaquin

Goblin Queen (She/Her/Hers)

iserith

Magic Wordsmith

Greg Bradburn

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Kevtron

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iserith

Magic Wordsmith

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