How Bardic Inspiration Works in 5e
As a Bonus Action a Bard gives an ally within 60 feet a die; once within the next hour, when that ally fails a D20 Test, they can roll it and add it to the d20. Most class features help the person who has them. Bardic Inspiration helps someone else. A Bard spends a Bonus Action, an ally pockets a die, and later that die turns a miss into a hit. Here is the rule, what each die size buys, and how the College of Lore turns the same die against the enemy.
The rule
The Bard gets it at level 1:
As a Bonus Action, you can inspire another creature within 60 feet of yourself who can see or hear you. That creature gains one of your Bardic Inspiration dice. A creature can have only one Bardic Inspiration die at a time.
And the ally uses it like this:
Once within the next hour when the creature fails a D20 Test, the creature can roll the Bardic Inspiration die and add the number rolled to the d20, potentially turning the failure into a success. A Bardic Inspiration die is expended when it's rolled.
Three things in those lines decide how the die plays:
- Another creature. A Bard can't inspire themself.
- After a failure. The ally rolls the d20, learns it failed, and only then decides. The die never goes on a roll that already worked.
- A D20 Test. The SRD names three: "ability checks, saving throws, and attack rolls." Damage rolls don't qualify.
The die lasts an hour, then it's gone. One per creature at a time, so a second Bonus Action on the same ally does nothing until the first die is used.
How many, and how big
You can confer a Bardic Inspiration die a number of times equal to your Charisma modifier (minimum of once), and you regain all expended uses when you finish a Long Rest.
A Bard with Charisma 16 has three uses a day at level 1. The die grows: "a d8 at level 5, a d10 at level 10, and a d12 at level 15."
Level 5 changes the budget. Font of Inspiration: "You now regain all your expended uses of Bardic Inspiration when you finish a Short or Long Rest. In addition, you can expend a spell slot (no action required) to regain one expended use." With Charisma 16 and two Short Rests, that is nine dice a day before a single slot is spent. Before level 5, three dice must last until morning.
At level 18, Superior Inspiration: "When you roll Initiative, you regain expended uses of Bardic Inspiration until you have two if you have fewer than that."
What the die is worth
Because the ally rolls it only after failing, every die lands where it can help. The question is how often it closes the gap. A Fighter with +5 to hit swings at a Goblin Warrior, AC 15. The swing lands 55% of the time; a natural 1 still misses whatever the die says.
| Bardic die | Hits, with the die | Misses it rescues |
|---|---|---|
| none | 55% | |
| d6 (level 1) | 72.5% | 39% |
| d8 (level 5) | 77.5% | 50% |
| d10 (level 10) | 81% | 58% |
| d12 (level 15) | 83.3% | 63% |
Saving throws have no natural 1 rule, so the die can rescue any roll close enough. A Fighter with Wisdom +1 facing a DC 13 save passes 45% of the time:
| Bardic die | DC 13 save | DC 15 save |
|---|---|---|
| none | 45% | 35% |
| d6 | 62.5% | 52.5% |
| d8 | 67.5% | 57.5% |
| d10 | 72.5% | 62.5% |
| d12 | 77.1% | 67.5% |
A d6 adds 17.5 points either way. That is the most useful number in this post: at level 1, a Bardic die turns a bit more than a sixth of all rolls from fail to pass, on any D20 Test.
Compare Heroic Inspiration, a full reroll: the same Fighter's swing goes from 55% to 79.75% (see Heroic Inspiration). A d6 is weaker than a reroll; a d10 is better. One creature can hold both, and both wait for the failure.
Where to put it
The die is worth most where one failed roll costs the most. A save against a spell that takes a character out of the fight, an Athletics check to stop a fall, the last swing at a foe on 2 Hit Points. It is worth least on the ally who rarely fails: a +7 attack against AC 12 hits 80% of the time, so the die sits unused most fights.
Hand it out early. The Bonus Action is the real cost, and on the turn a fight starts the Bard often has nothing better to do with it. A die given before the doors open still counts: it lasts the hour.
Cutting Words, the same die backwards
The College of Lore gets this at level 3:
When a creature that you can see within 60 feet of yourself makes a damage roll or succeeds on an ability check or attack roll, you can take a Reaction to expend one use of your Bardic Inspiration; roll your Bardic Inspiration die, and subtract the number rolled from the creature's roll, reducing the damage or potentially turning the success into a failure.
Again the Bard waits for the result. An Ogre swings its Greatclub (+6, 13 damage on average) at a Fighter with AC 16. It hits 55% of the time. Cutting Words with a d6 on each hit drops that to 37.5%; with a d8, 32.5%. A natural 20 still hits: the SRD says a natural 20 "hits regardless of any modifiers or the target's AC."
The Bard has a choice on every hit: cut the attack roll now, or wait and cut the damage. Cutting the damage with a d6 always takes off 3.5 on average. Cutting the attack saves all 13, but only if the die turns the hit into a miss. The margin decides:
| Ogre's total beats AC 16 by | d6 turns it to a miss | Damage saved, cutting the attack |
|---|---|---|
| 0 | 100% | 13 |
| 1 | 83% | 10.8 |
| 2 | 67% | 8.7 |
| 3 | 50% | 6.5 |
| 4 | 33% | 4.3 |
| 5 | 17% | 2.2 |
| 6 or more | 0% | 0 |
The rule of thumb: if the attack beats the AC by 4 or less, cut the attack. By 5 or more, wait for the damage. On a natural 20, always the damage.
Peerless Skill
At level 14, a Lore Bard can use the die on themself, with a better deal than anyone else gets:
When you make an ability check or attack roll and fail, you can expend one use of Bardic Inspiration; roll the Bardic Inspiration die, and add the number rolled to the d20, potentially turning a failure into a success. On a failure, the Bardic Inspiration isn't expended.
Ability checks and attack rolls only, not saves. But a die that comes back when it doesn't work is never wasted.
At the table
Bards: say "you have Bardic Inspiration" out loud and put a real die by the ally's sheet, the right size. Allies: say "I failed, I'll use it" before the GM narrates the result. GMs: let players add the die after you announce a miss; that is the rule, not a favour.
For the full turn the Bonus Action fits into, see Your Turn in Combat. For the saves worth spending it on, see Saving Throws, and for the checks, Ability Checks and DCs.
This work includes material from the System Reference Document 5.2.1 ("SRD 5.2.1") by Wizards of the Coast LLC, available at dndbeyond.com/srd. The SRD 5.2.1 is licensed under the Creative Commons Attribution 4.0 International License.
