How to Determine Attack Bonus in DnD 5e


The question of how to determine Attack Bonus in Dungeons and Dragons 5e is quite complex. This stems from multiple factors. The main of which is the circumstances, as your attack roll will not be the same in one encounter as in another.
The reasons for this are many: Your character has progressed in level, you’ve acquired a new enchanted item, you or someone in your party has unlocked an ability that grants you a bonus to your attack modifier or the spell you are about to cast.

So let’s look at each of these individually. So that we may get a better understanding of them. How they affect your attack and damage rolls, and how the process of calculating them works for the next time that you play. Starting with…

How to Determine Attack Bonus in DnD 5e

We must answer the most important question first. In a previous article we looked at how to calculate damage, let’s expand on that now.

When calculating for your Attack Bonus the basic formula to follow is this:

1 d20 roll + Ability Score Modifier + Proficiency Modifier + Magic Weapons Bonus + Class Bonus + Spell Bonus = Attack Roll

Pretty simple right?
There is one thing to note here though. In regards to the types of bonuses that you can get, some are “flat” while others can vary. But what do I mean by this?

There are certain bonuses that always offer you the same boost to the attack roll. Things like enchanted items always offer you the predetermined amount as written in the Player’s Handbook. While things like the 1st Level Spell “Bless” gives you an extra 1d4 dice to roll.
See the difference?

Now that we’ve looked at the formula on how to determine your attack bonus, let’s look at each element individually.

Analyzing Each Element Individually

“If you know the enemy and know yourself, you need not fear the result of a hundred battles…” – Sun Tzu

It’s important to know each tool at your disposal, so that you may use it optimally. That is why we’ll look at each of the parts in the formula individually now.

The d20

The d20 roll is straightforward. You either get lucky or you don’t. And if you’ve landed a natural 20 then good luck – you’ve got a pot of gold.

Ability Score Modifiers

Building your character properly is the most important part – it determines your efficiency later on. Understanding yourself is the most important element. This goes for a spellcaster just as much as it goes for a melee fighter.

Proficiency Modifier

This ties in with the previous point. If you’ve built your character right, by lvl 17 you should have a +6 proficiency; that bonus is nothing to scoff at. Either you are proficient – or you are not. It’s that simple, but still; there are levels to it.

Magic Weapons Bonus

Throughout your adventures you might find a magical weapon you can use, don’t pass this opportunity up. If not, ask another player who can enchant or craft a magical item for you. Remember, something as easy as silvering your weapons which only costs 100gp can help you greatly in fights against certain creatures.
Any atk bonus helps when you have to fight a specific type of enemy. And if you add a weapon with silver into the mix, like in our previous example. Then you should be golden.

Class Bonuses

The lesson to be taken here is simple. Play to your strengths, and exploit the enemy’s weaknesses. For example. If you’re playing as a Paladin and use Divine Smite on an Undead creature you get 1d8 dice to roll on top of other 1d8 dice that you get.
A spell attack bonus on top of a melee attack will see the enemy go down real quick.

Spell Bonus

It’s great folly to go into an encounter unprepared. Anybody who has played an MMO like WoW knows how important buffs are. The same is applicable in DnD 5e. If the character you are playing can apply any sort of bonus with a spell to yourself or your allies – do it.


That’s basically all that you need to know about how to determine Attack Bonus in DnD 5e.
The formula is simple, even though there are multiple elements to take into consideration.

Just as long as you remember to calculate each part properly you should see the numbers rise quickly.

Of course, there is one final element that is important to mention here – your DM.

Your DM’s rules are superior to even Xanathar’s. That is why you should discuss and agree on which rules you will use in your games. Some DM’s forego magical weapons and items because they just increase the amount of time one has to spend calculating each turn.

For any other specific information that you may want to know about your class or a weapon in question, consult the Player’s Handbook. From melee weapons to the basics of a finesse weapon, all the way to the ability modifiers for the class in question. That’s the best place to find all the information you need.

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