[RPG] How to calculate passive perception for a monster


This is a really simple one but I just want to be 100% clear I'm doing this right:

Just starting out with D&D as a DM (using the Starter Set rulebook and the 5E Player's Basic Rules on the official site).

Let's say my group meets a Goblin. It has -1 WIS, so its passive perception score is 9 (-1 + 10). I get this.

If they meet an Adult Black Dragon, it has +1 WIS, but also +11 Perception as a skill. Does this mean its passive perception score is 21 (eg. +11 + 10)? Or is it just 11 (+1 + 10)?

Sorry this is basic – just want to make sure I understand it.

Best Answer

Yes, the Adult Black Dragon's passive perception is 21.

A Passive Ability Check is calculated by taking 10 and adding the relevant Ability Score, then your Proficiency Bonus (if applicable(or double if you have Expertise)), and then any other relevant modifiers.

In short, instead of a roll, you pretend that the creature rolled a 10 and add the bonuses as normal.