This update brings a long-requested feature to the dnd5e system: automatic armor class calculation. This D&D5E system update was championed by Kim (Fyorl) who led and organized the community efforts to implement the features in this update. Big thanks are due to all the contributors!

screenshot of NPC sheet showing splint, shield and calculated AC value with cog visible

An NPC with their armor equipped

Players and DMs alike will be able to configure their character's or NPC's armor class using a new dialog on the sheet that comes pre-configured with some common options such as Draconic Resilience or Unarmored Defense.

screenshot of armor configuration dialog

By default a character will use whatever equipped armor they have to calculate their AC, according to the rules you've come to expect. They may also opt to select one of the other pre-configured armor calculations. For those with homebrew needs, there is also an option to input an entirely custom armor calculation formula. Finally, those who wish to opt-out entirely of automatic armor class calculation can input whatever value they like for their character's AC, just as before.

screenshot of armor tooltip with armour, shield, and ring of protection

Hovering over the armor class value on the sheet will display a tooltip containing a breakdown of how that armor class value has been achieved.

Active Effects

All of these new components to armor class calculation (ac.flat, ac.base, ac.shield, ac.bonus, and ac.cover) are targetable with Active Effects, opening the door to a variety of new magic item and in-combat effects. See the SRD item compendium for some examples of this, such as the Ring of Protection, and Robe of the Archmagi.


Those of you with existing worlds should expect no major disruptions with this update. All of your existing Actors will have been migrated to preserve their armor class values. To start using the new automatic armor class calculation on those migrated Actors, all you need to do is open their armor class configuration and delete the large, top number, removing the armor class override.

Any Actors you have in world-level compendia will have also received the same treatment. You will notice that the Starter Heroes and the SRD monsters are all now using automatic armor class calculations (where appropriate). If you would like to apply this to your own world-level compendia or are a dnd5e module developer and wish to migrate the compendia provided with your module, we have provided a small migration utility to help. You may run the following in the console or as a script macro:


This will migrate the given compendium, removing the armor class override from any Actors that have armor and/or shield items equipped. If you need to apply the default migration which preserves AC values exactly, you may run the normal dnd5e migration as usual with migrateCompendium.

Patch Notes

While armor class was the main focus of this release, there were still plenty of other fixes and improvements that were added.


  • Automatic armor class calculation.
  • Added support for metric units in the system settings. This just changes labels and does not automatically convert existing data.
  • Item rarity is now a drop-down and can be configured by modules through CONFIG.DND5E.itemRarity.
  • Tool items now have a tool type category that they can belong to.
  • Active Effects transferred from items which are equippable or have an attunement requirement will now no longer provide their effect if they aren't equipped or attuned.
  • A character may now select individual weapon, armor, and tool proficiencies instead of only whole categories.
  • The sorting of proficiencies in the proficiency selector dialog is now localisation-aware.
  • Added a restCompleted hook for modules that fires whenever a character finishes a long or short rest.
  • Eligible class skills can now be configured on class sheets.
  • Vehicles may now have a land, air, or water type.

Bug Fixes

  • Items that are added from a compendium and then renamed no longer continue to stack when another of the original item is added again from the compendium.
  • Fixed some issues around traits like Remarkable Athlete or Jack of all Trades persisting their proficiency changes to the actor even after the traits are removed.
  • Fixed the level at which the Champion's Additional Fighting Style feature is received.
  • Fixed the level at which the Paladin's Spellcasting feature is received.
  • Placing an Actor with custom token sizes into a compendium no longer replaces those custom token sizes when you again retrieve that creature from the compendium.
  • The dialog for selecting features on level up no longer scrolls off the screen if there are too many features.
  • Fixed encumbrance calculation.
  • Fixed polymorphing a token resetting the token's vision even if 'Keep Vision' was selected.


Thanks to Phil Best, Jeff 'Arbron' Hitchcock, Iñaki 'ccjmk' Guastalli, Varriount, and all those who submitted bug reports and issues.