When you play Dungeons & Dragons 5th edition, you will probably at some point notice you have something called Hit Dice (HD), and wonder what they even do or how a party of barbarians is supposed to recover from all the near-death experiences they have. To summarize, Hit Dice are a reservoir of natural healing all creatures have.
How to use Hit Dice
In order to spend Hit Dice, you need to take a rest, specifically a Short Rest. This allows you to expend and roll as many Hit Dice as you want from your available pool, adding your Constitution Modifier to the result in order to heal. The size of your pool is equal to your characterlevel, for example, a 5th level Fighter will have a maximum of five Hit Dice (in this case, D10s).
Another time to roll Hit Dice is when you level up, you can either take the average result of your new Hit Die (so if you gained a D8 and use an average of 5), or you can roll. This allows you to roll the Hit Die you gain from your new class level (which determines its size) once, adding your Constitution Modifier, and increasing your current and maximum HP by that amount; using a Hit Die in this way doesn’t expend one from your available pool. No matter what you roll, or how low your Constitution modifier is, you always gain a minimum of 1 Hit Point each level.
These are the two uses available to all characters, some features will allow you to use your Hit Dice in other ways. An example of this is the Dwarf exclusive feat Dwarven Fortitude which, among other things, allows you to roll a single Hit Die when you take the Dodge action, regaining Hit Points as if you had rolled it during a short rest.
How do i get My Hit Dice back?
Whilst you spend Hit Dice on a short rest, you regain them on a long rest… well, some of them at least.
When you finish a long rest, you regain a number of Hit Dice up to half of your maximum number of Hit Dice. So if you’re a 6th level character, you can recover up to 3 spent Hit Dice. This means it’s very possible to run out of Hit Dice whilst you’re adventuring, if you’re consistently spending more than half of your Hit Dice pool each day.
Tip: If you ever need to divide a number, always round down unless you’re told to round-up by the feature/rule. So for Hit Dice, if you’re a 5th level character, you can recover up to 2 Hit Dice on a long rest because 2.5 would round down to 2.
What size Hit Die do I use?
Speaking of Hit Die sizes, each class gains a certain Hit Die. Such as, Barbarians getting a d12, Fighters a d10, Rogues a d8, and Wizards a d6. Note there are no classes with a d4 Hit Die, as that’s really low and should be reserved for powerful homebrew classes that can’t take a hit. However, if you multiclass, you don’t pick one or the other, but gain another Hit Die from the other class. For example: a level 2 Barbarian with 3 levels of Rogue would have 2d12 and 3d8 for Hit Dice, of which you choose which die to expend whenever you take a short rest, so long as you have them remaining.
What about monsters?
Now for you DMs out there, Monsters do get Hit Dice, which are used when rolling for HP (only do this for single/long-running foes, or if you can do it really fast), or setting HP which affects CR. The size of these Hit Dice depends on creature size as seen on the table on pg. 276 of the DMG, which might help with some homebrew you had cooking up.
As always, I hope this was helpful to those who read it, comment below to tell us what you think. May the dice keep rolling in your favor!