Working out if you hit a target requires a bit of fairly simple math. Here’s what you need to do:
- Choose a target: Decide what it is you want to attack
- Roll to hit: Roll a d20 and see what number you roll
- Add modifiers: Look at the ability score you’re using to attack with, add the modifier for that ability score to the d20 roll. If you’re proficient with the weapon (or attacking with a spell), you should also add your proficiency bonus.
- Add any other modifiers: Some weapons and abilities may give you additional bonuses to your attack rolls such as an artificer’s infusion. Make sure you add these when determining your score
- Compare against AC: The DM will do this for you, but if your score is equal to or higher than the target’s AC, then you hit the target
To put the calculation in a formula:
Attack roll + ability score modifier + proficiency bonus + other bonuses = attack score
If your attack score is equal to or higher than the AC of the target, then it’s a hit.
As an example, you attack with a greatsword with a strength of 16 (+3 modifier) and a proficiency bonus of 2 (assuming you’re proficient with a greatsword). You roll to hit and get a 12. This means your score will be:
12 + 3 + 2 = 17
Your enemy has an AC of 17, this means you hit because you only need a score equal to or greater than the target’s AC.
Which ability score do I use?
It depends on what you’re attacking with. If you’re making a weapon attack, then you use strength unless the weapon has the finesse or ranged properties. If a weapon has the ranged property, you use dexterity, if it has the finesse property, you can choose to use either strength or dexterity.
If you’re making a spell attack, then you use whichever ability is your spellcasting ability which will be stated in you class description; intelligence, wisdom or charisma.
Advantage and disadvantage
Sometimes you’ll be fighting in a situation where your ability to hit is improved or impaired. Mechanically, this is called having advantage of disadvantage. If you have advantage, you roll the d20 to hit twice and use the highest roll. If you have disadvantage, you do the same but must use the lowest roll.
Critical hits and critical misses
If you roll a 20, it is always a hit, regardless of the modifiers added to the roll and incurs a critical hit meaning you do more damage.
If you roll a 1, it is always a miss regardless of any modifiers you add to the score.
Ask Dungeon Mister: Submit your question
Got a question of your own? Use our form below to submit your own questions and we’ll do our best to provide an answer: