Melee weapon attacks will use your Str modifier, you may instead use your Dex modifier if you’re using a weapon with the Finesse property.
Ranged weapon attacks will use your Dex modifier, if you’re making the attack with a thrown weapon then you use the same modifier as you would to make a melee attack. For example a handaxe will use Str when thrown, but a dagger can use either Str or Dex, because a dagger is a Finesse weapon.
If you are proficient with the weapon you are using then you add your proficiency bonus to your ability score mod. A Fighter making a melee attack with a longsword would use the following to determine their Attack Bonus:
Str Mod + Proficiency = Attack Bonus
A Ranger making a ranged attack with a longbow would use the following to determine their Attack Bonus:
Dex Mod + Proficiency = Attack Bonus
Note: Some class features allow you to use alternative stats for weapon attacks, these include the Monk’s Martial Arts, the Hexblade Warlock patron’s Hex Warrior, and the Battle Smith Artificer’s Battle Ready. The Shillelagh cantrip is also an exception to these general rules.
Spell attacks are more straightforward than their weapon counterparts, as you’re always proficient in a spell you are casting:
Spellcasting Mod + Proficiency = Spell Attack Bonus
The ability score that you use for your spellcasting modifier is dependent on where the spell you are casting came from. This is straightforward for single classed spell casters, but if you are a multiclassed spellcaster (and those classes use different spellcasting stats) then you need to be aware which stat the spell you are casting uses.
For example a Wizard has the Firebolt cantrip and then takes a one level dip in Sorcerer and decides to choose Shocking Grasp. As Firebolt is a Wizard spell it uses the PC’s Int as the spellcasting mod, but Shocking Grasp will use Cha because it is a Sorcerer spell. This also applies to spells gained from feats and races, they may have different casting stats so it’s always advisable to double check and make note of which spells use other stats.
How Can You Increase Your Attack Bonus?
Besides increasing your Attack Bonus by increasing your primary stat and levelling up to gain a higher proficiency bonus, there are some other ways to increase your Attack Bonus. Here are some examples:
|Name||Type||Applies to||Bonus Granted|
|Archery||Fighting Style||Attacks made with ranged weapons||2|
|Bless||1st level spell||All attacks||+1d4|
|Favored by the Gods||Divine Soul ability||Any attack that misses||+2d4|
|Guided Strike||Channel Divinity (War Domain and Oath of Conquest)||Any attack||10|
|Magic Weapon||Magic Item||Attacks with that weapon||+1,+2, or +3|
|Magic Focus||Magic Item||Spells cast through that focus||6|
|Saving Face||Hobgoblin Ability||An attack that misses||Up to +5|
There we have it, it’s not difficult to work out your Attack Bonus when you know how and in practice you’ll be able to work it out once and make note of it as it won’t increase that often. Now that you’re informed on Attack Bonuses and some ways to increase them go out and hit that bullseye, well assuming you don’t roll a natural one of course!