I have a barbarian with unarmored defense. My base AC is 18 with my dex mod. When I put on armor, the sheet should drop the unarmored defense bonus, but it does not. If i put on a breast plate, it should drop to 14, but it does not. when i put on a breastplate +3, it should be 17 (i think... 10 base + 4 dex mod + +3 armor). Instead, the ac goes to 20.
I have a barbarian with unarmored defense. My base AC is 18 with my dex mod. When I put on armor, the sheet should drop the unarmored defense bonus, but it does not. If i put on a breast plate, it should drop to 14, but it does not. when i put on a breastplate +3, it should be 17 (i think... 10 base + 4 dex mod + +3 armor). Instead, the ac goes to 20.
You always use the highest available modifier. In the case of unarmored defense, you're right that you can't use it while wearing armor, but you forgot one thing in your calculation. Breastplate's base is 14, not 10. So the calculation is:
14 (Breastplate) + 2 (Dex mod, max 2) + 3 (Magic bonus) = 19. You might have a +1 somewhere else that's being calculated, not sure where without seeing the full sheet.
Medium Armor Master increases the Dex threshold to +3. That's the difference.
To elaborate: The original post you made assumed the full bonus from your Dex (which you don't get with medium armor, it's usually a max of +2 unless something allows you to use more, such as Medium Armor Master allowing +3 from your Dex or the Serpent Scale Mail from Candlekeep Mysteries having no such restrictions). It also didn't take into account the base defense from the armor, which overrides your Unarmored Defense entirely.
I have a barbarian with unarmored defense. My base AC is 18 with my dex mod. When I put on armor, the sheet should drop the unarmored defense bonus, but it does not. If i put on a breast plate, it should drop to 14, but it does not. when i put on a breastplate +3, it should be 17 (i think... 10 base + 4 dex mod + +3 armor). Instead, the ac goes to 20.
You always use the highest available modifier. In the case of unarmored defense, you're right that you can't use it while wearing armor, but you forgot one thing in your calculation. Breastplate's base is 14, not 10. So the calculation is:
14 (Breastplate) + 2 (Dex mod, max 2) + 3 (Magic bonus) = 19. You might have a +1 somewhere else that's being calculated, not sure where without seeing the full sheet.
Please, have at it.
https://www.dndbeyond.com/characters/64757559
EDIT - Is it maybe from "athlete"?
Medium Armor Master increases the Dex threshold to +3. That's the difference.
To elaborate: The original post you made assumed the full bonus from your Dex (which you don't get with medium armor, it's usually a max of +2 unless something allows you to use more, such as Medium Armor Master allowing +3 from your Dex or the Serpent Scale Mail from Candlekeep Mysteries having no such restrictions). It also didn't take into account the base defense from the armor, which overrides your Unarmored Defense entirely.
Excellent. I thank you for the assistance. May the dice roll to your advantage.