To calculate challenge rating in 5e, you need to consider both the defensive and offensive statistics of a creature. A creature with a 1/8 challenge rating (CR) typically has an AC of 13, 7-35 hit points, and a +3 attack bonus. Compared to a CR 10 creature, which has an average of 17 AC, 206-220 hit points, and a +7 attack bonus.
On page 274 of the Dungeon Master’s Guide, you can find a table that shows the various defensive and offensive elements that go into determining a creature’s monster rating:
| — Defensive — | — Offensive — | ||||||
|---|---|---|---|---|---|---|---|
| CR | Xp | +Prof. Bonus | AC | Hit Points | Attack Bonus | Damage/Round | Save DC |
| 0 | 10 | +2 | 13 | 1-6 | +3 | 0-1 | 13 |
| 1/8 | 25 | +2 | 13 | 7-35 | +3 | 2-3 | 13 |
| 1/4 | 50 | +2 | 13 | 36-49 | +3 | 4-5 | 13 |
| 1/2 | 100 | +2 | 13 | 50-70 | +3 | 6-8 | 13 |
| 1 | 200 | +2 | 13 | 71-85 | +3 | 9-14 | 13 |
| 2 | 450 | +2 | 13 | 86-100 | +3 | 15-20 | 13 |
| 3 | 700 | +2 | 13 | 101-115 | +4 | 21-26 | 13 |
| 4 | 1,100 | +2 | 14 | 116-130 | +5 | 27-32 | 14 |
| 5 | 1,800 | +3 | 15 | 131-145 | +6 | 33-38 | 15 |
| 6 | 2,300 | +3 | 15 | 146-160 | +6 | 39-44 | 15 |
| 7 | 2,900 | +3 | 15 | 161-175 | +6 | 45-50 | 15 |
| 8 | 3,900 | +3 | 16 | 176-190 | +7 | 51-56 | 16 |
| 9 | 5,000 | +4 | 16 | 191-205 | +7 | 57-62 | 16 |
| 10 | 5,900 | +4 | 17 | 206-220 | +7 | 63-68 | 16 |
| 11 | 7,200 | +4 | 17 | 221-235 | +8 | 69-74 | 17 |
| 12 | 8,400 | +4 | 17 | 236-250 | +8 | 75-80 | 18 |
| 13 | 10,000 | +5 | 18 | 251-265 | +8 | 81-86 | 18 |
| 14 | 11,500 | +5 | 18 | 266-280 | +8 | 87-92 | 18 |
| 15 | 13,000 | +5 | 18 | 281-295 | +8 | 93-98 | 18 |
| 16 | 15,000 | +5 | 18 | 296-310 | +9 | 99-104 | 18 |
| 17 | 18,000 | +6 | 19 | 311-325 | +10 | 105-110 | 19 |
| 18 | 20,000 | +6 | 19 | 326-340 | +10 | 111-116 | 19 |
| 19 | 22,000 | +6 | 19 | 341-355 | +10 | 117-122 | 19 |
| 20 | 25,000 | +6 | 19 | 356-400 | +10 | 123-140 | 19 |
| 21 | 33,000 | +7 | 19 | 401-445 | +11 | 141-158 | 20 |
| 22 | 41,000 | +7 | 19 | 446-490 | +11 | 159-176 | 20 |
| 23 | 50,000 | +7 | 19 | 491-535 | +11 | 177-194 | 20 |
| 24 | 62,000 | +7 | 19 | 536-580 | +11 | 195-212 | 21 |
| 25 | 75,000 | +8 | 19 | 581-625 | +12 | 213-230 | 21 |
| 26 | 90,000 | +8 | 19 | 626-670 | +12 | 231-248 | 21 |
| 27 | 105,000 | +8 | 19 | 671-715 | +13 | 249-266 | 22 |
| 28 | 120,000 | +8 | 19 | 716-760 | +13 | 267-284 | 22 |
| 29 | 135,000 | +9 | 19 | 760-805 | +13 | 285-302 | 22 |
| 30 | 155,000 | +9 | 19 | 805-850 | +14 | 303-320 | 23 |
Here’s how to use that table:
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Defensive Challenge Rating. First, look at your monster’s hit points and note the associated challenge rating. Then, look at the suggested AC for that hit point value. If the monster’s AC is at least two points higher or lower than challenge rating suggested by its hit points, adjust the CR up or down by 1 for every 2 points of difference.
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Offensive Challenge Rating. Determine the monster’s average damage per round. Note that the “damage per round” numbers in this table assume that all attacks land. For example, if a monster has multiattack and each of its attacks deals an average of 5 damage, its damage per round is 10 (even though, realistically, not all of its attacks will land, and its real DPR will be lower) (DMG 277 – Step 11).
Once you know the monster’s damage per round, find it on the table above and note the challenge rating associated with it. Then, look at the attack bonus or save DC (whichever is more relevant for the monster’s damage) suggested for that challenge rating. If it’s at least two points higher or lower than the challenge rating indicated by its damage per round, adjust the CR up or down by 1 for every 2 points of difference.
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Average Challenge Rating. Finally, average the defensive and offensive challenge ratings. Round the average up or down to the nearest challenge rating that exists. For example, if your monster’s offensive challenge rating is 9 and their defensive challenge rating is 6, their final challenge rating is 8 (7.5 rounded up).
Once you’ve determined a monster’s CR, you can assign its proficiency bonus.
Dungeon Master’s Guide, page 274-7
Other Considerations for a Creature’s Challenge Rating
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Resistances and Immunities. A creature with resistances or immunities has more “effective hit points,” which you need to consider as its actual hit points when determining its Defensive Challenge Rating. The DMG suggests the following multipliers, dependent on what CR bracket the creature belongs to:
Expected CR Resistance HP Mod Immunity HP Mod 1-4 x2 x2 5-10 x1.5 x2 11-16 x1.25 x1.5 17+ x1 x1.25 -
Special Traits, Spellcasting, Actions, and Reactions. If special traits, spells, actions, and reactions significantly alter a monster’s offensive or defensive CR (by increasing their damage per round or effective hit points, for example), it may increase a creature’s CR.
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Flying Speed. A creature with flying speed has +2 effective AC when determining its defensive challenge rating — if it can deal damage at range and currently has a CR of 10 or lower.
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Saving Throw Proficiencies. If a monster has three or more saving throw bonuses, it has +1 effective AC when determining its defensive challenge rating; if it has 4 bonuses, it has +2 effective AC; if it has 5+ bonuses, it has +4 effective AC.
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Monster Features. Many monster features can increase their CR by changing their offensive or defensive challenge ratings. Here are all of the listed monster features that impact a monster’s CR in some way:
| Feature | Effect on CR |
|---|---|
| Aggressive | Increase the monster’s effective per-round damage output by 2. |
| Ambusher | Increase the monster’s effective attack bonus by 1. |
| Angelic Weapons | Increase the monster’s effective per-round damage output by the amount noted in the trait. |
| Avoidance | Increase the monster’s effective AC by 1. |
| Blood Frenzy | Increase the monster’s effective attack bonus by 4. |
| Breath Weapon | For the purpose of determining effective damage output, assume the breath weapon hits two targets, and that the target each fails its saving throw. |
| Brute | Increase the monster’s effective per-round damage by the amount noted in the trait. |
| Charge | Increase the monster’s damage on one attack by the amount noted in the trait. |
| Constrict | Increase the monster’s effective AC by 1. |
| Damage Transfer | Double the monster’s effective hit points. Add one-third of the monster’s hit points to its per-round damage. |
| Dive | Increase the monster’s damage on one attack by the amount noted in the trait. |
| Elemental Body | Increase the monster’s effective per-round damage by the amount noted in the trait. |
| Enlarge | Increase the monster’s effective per-round damage by the amount noted in the trait. |
| Fiendish Blessing | Apply the monster’s Charisma modifier to its actual AC. |
| Frightful Presence | Increase the monster’s effective hit points by 25% if the monster is meant to face characters of 10th level or lower. |
| Horrifying Visage | Increase the monster’s effective hit points by 25% if the monster is meant to face characters of 10th level or lower. |
| Innate Spellcasting | The impact that Innate Spellcasting has on a monster’s challenge rating depends on the spells that the monster can cast. Spells that deal more damage than the monster’s normal attack routine and spells that increase the monster’s AC or hit points need to be accounted for when determining the monster’s final challenge rating. |
| Legendary Resistance | Each per-day use of this trait increases the monster’s effective hit points based on the expected challenge rating. |
| Magic Resistance | Increase the monster’s effective AC by 2. |
| Martial Advantage | Increase the monster’s effective per-round damage by the amount gained by this trait. |
| Nimble Escape | Increase the monster’s effective AC and effective attack bonus by 4 (assuming the monster hides every round). |
| Pack Tactics | Increase this monster’s effective attack bonus by 1. |
| Parry | Increase the monster’s effective AC by 1. |
| Possession | Double the monster’s effective hit points. |
| Pounce | Increase the monster’s effective damage for 1 round by the amount it deals with the bonus action gained from this trait. |
| Psychic Defense | Apply the monster’s Wisdom modifier to its acual AC if the monster isn’t wearing armor or wielding a shield. |
| Rampage | Increase the monster’s effective per-round damage by 2. |
| Regeneration | Increase the monster’s effective hit points by 3 * the number of hit points the monster regenerates each round. |
| Relentless | Increase the monster’s effective hit points based on the expected challenge rating: 1-4, 7 hp; 5-10, 14 hp; 11-16, 21 hp; 17 or higher, 28 hp. |
| Shadow Stealth | Increase the monster’s effective AC by 4. |
| Spellcasting | The impact that Spellcasting has on a monster’s challenge rating depends on the spells that the monster can cast. Spells that deal more damage than the monster’s normal attack routine and spells that increase the monster’s AC or hit points need to be accounted for when determining the monster’s final challenge rating. |
| Stench | Increase the monster’s effective AC by 1. |
| Superior Invisibility | Increase the monster’s effective AC by 2. |
| Surprise Attack | Increase the monster’s effective damage for 1 round by the amount noted in the trait. |
| Swallow | Assume the monster swallows one creature and deals 2 rounds of acid damage to it. |
| Undead Fortitude | Increase the monster’s effective hit points based on the expected challenge rating: 1-4, 7 hp; 5-10, 14 hp; 11-16, 21 hp; 17 or higher, 28 hp. |
| Web | Increase the monster’s effective AC by 1. |
Dungeon Master’s Guide page 280-1
Example Challenge Rating Calculation 5e
I create a monster with the following statistics:
| AC | Hit Points | Attack Bonus | Damage/Round | Save DC |
|---|---|---|---|---|
| 15 | 135 | 6 | 25 | 14 |
It also has resistance to nonmagical weapon damage and the Avoidance feature.
Here’s how to calculate its CR:
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Defensive Challenge Rating. My monster has 135 hit points, which suggests a CR of 5. However, with that expected CR and nonmagical weapon damage, this moster’s “effective HP” is 202 (135 x 1.5). This suggests a CR of 9.
With the Avoidance feature, the monster’s effective AC goes from 15 to 16. This is within range of a CR 9 monster, so we are finished calculating the monster’s Defensive Challenge Rating.
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Offensive Challenge Rating. This monster’s damage per round is 25, which indicates a CR of 3. However, since their attack bonus of +6 indicates a CR of 5, we need to increase that CR of 3. The difference here in CR is 2, so we increase the original CR 3 to an Offensive Challenge Rating of 4.
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Average Challenge Rating. The monster’s Defensive Challenge Rating is 9, and its Offensive Challenge Rating is 4, so its Average Challenge Rating is 7 (6.5 rounded up). Finished!
