If I use static damage from monsters, how do I calculate the value on critical hits? I can't just double the value, because that includes the static modifier. Should I recalculate the damage on the fly (so, if the monster usually has (7) d8 + 3, I make it (11) 2d8 + 3)? That's kind of pain in the ass. Or do the monsters not double their static damage on critical hits and only get the benefit of the guaranteed hit? Alternatively, I could decide that I roll on crits.

Are there official rules the govern this?


2 Answers 2


The Dungeon Master's Guide has rules for handling this case:

On the Monsters and Critical Hits section (DMG page 248), it states what to do in the case of a monster critical hit when using average damage:

When the monster scores a critical hit, roll all the damage dice associated with the hit and add them to the average damage. For example, if a goblin normally deals 5 (1d6 + 2) slashing damage on a hit and scores a critical hit, it deals 5 + 1d6 slashing damage.

So the suggestion is simply to roll the damage dice and then add the average damage. In your case, the damage of (7) d8 + 3 simply becomes 1d8+7 when a mosnter scores a critical hit.

  • 2
    \$\begingroup\$ Nice find! Also good to know that I've been doing this "right" all along (when I use average damage, that is). \$\endgroup\$
    – NathanS
    Commented Nov 15, 2019 at 17:16
  • \$\begingroup\$ Thanks a lot! I think I need to re-read all the books again to catch all these pieces! \$\endgroup\$
    – gruszczy
    Commented Nov 15, 2019 at 19:19

Are there official rules on this?

Yes, per Sdjz's answer..
But it requires a die roll.
You can do it without any dice rolling if you like.

What have I seen done that is fast and simple?

A critical hit when using average damage is "Max roll +1"
If I am doing 1d4, it becomes 5 + modifier.
If I am doing 1d6, it becomes 7 + modifier.

Easy to keep track of in one's head:
When monster rolls a "Critical Hit, I add one to the max die value"
... you have to add the modifier anyway, critical hit or not.

No die roll required.

What do I do? I roll the dice. I got addicted to the dice rolling bit when I started playing, so even though the above method is faster, I still roll the dice.

As the number of dice rolled increase, you run into the matter of even number versus odd number. If monster damage is 2dx, 4dx, 6dx just double the average + modifier. If you have an odd number of dice, 3dx, 5dx, it's double the average +1 + modifier ... because the posted average in the books rounds fractions down

  • 2
    \$\begingroup\$ I think I prefer to roll as well, but this is a clever and convenient way to shortcut things for the sake of simplicity \$\endgroup\$ Commented Nov 15, 2019 at 17:46

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