This calculator module is built based on the official D&D 5th Edition Dungeon Master’s Guide (DMG) CR calculation guidelines.
The 5e CR Calculator module simplifies the complex process of determining a custom creature’s Challenge Rating (CR) by comparing its key Defensive and Offensive statistics against the standard benchmarks set by the Dungeon Master’s Guide.
5e CR Calculator
Suggested Challenge Rating (CR)
CR ?5e CR Calculator Formula and Adjustments
The Challenge Rating (CR) is determined by an iterative process that averages the Defensive CR and Offensive CR. This calculator follows the core rules:
2. Adjust Defensive CR based on AC deviation from expected value.
3. Determine Base Offensive CR from DPR.
4. Adjust Offensive CR based on Attack Bonus deviation from expected value.
5. Final CR = Average(Defensive CR, Offensive CR).
Variables Explained
- Hit Points (HP): The creature’s maximum health. Used to determine the base Defensive CR.
- Armor Class (AC): The creature’s difficulty to hit. Used to adjust the Defensive CR.
- Damage Per Round (DPR): The creature’s average damage output across three rounds. Used to determine the base Offensive CR.
- Highest Attack Bonus: The highest modifier the creature adds to its attack rolls. Used to adjust the Offensive CR.
Related Calculators
- 5e XP and Treasure Payout Calculator
- 5e Spell Save DC Calculator
- 5e Encounter Difficulty Adjuster
- 5e Monster Size & Type Template Generator
What is 5e CR Calculator?
Challenge Rating (CR) is the primary metric used in Dungeons & Dragons 5th Edition to gauge a monster’s strength and difficulty relative to a party of four adventurers. A creature with a CR equal to the party’s average level is considered a moderate challenge.
Creating custom monsters is a staple of good dungeon mastering, but balancing them requires rigorous assessment. This calculator automates the core math of the CR calculation process, allowing game masters to quickly estimate a balanced CR for their homebrew creations based on their raw combat stats.
It’s important to note that the final CR is merely a starting point. Special abilities, legendary actions, and resistances (like damage immunities) are factored in manually after the base calculation is complete.
How to Calculate 5e CR (Example)
- Input Stats: A monster has 100 HP, 14 AC, 22 DPR, and a +5 Attack Bonus.
- Find Base Defensive CR: 100 HP corresponds to an expected CR of 2. The expected AC for CR 2 is 13.
- Adjust Defensive CR: The monster’s 14 AC is +1 higher than the expected 13. Since the difference is less than $\pm 2$, the Defensive CR remains 2.
- Find Base Offensive CR: 22 DPR corresponds to an expected CR of 3. The expected Attack Bonus for CR 3 is +4.
- Adjust Offensive CR: The monster’s +5 Attack Bonus is +1 higher than the expected +4. Since the difference is less than $\pm 2$, the Offensive CR remains 3.
- Final CR: Average (Defensive CR 2, Offensive CR 3) = 2.5. This rounds up to a final **CR 3**.
Frequently Asked Questions (FAQ)
What if my monster has damage resistance or immunities?
Damage resistances (like resistance to cold damage) or immunities effectively increase a creature’s Hit Points. The DMG instructs you to multiply the creature’s effective HP by 1.5 (for resistance) or 2 (for immunity) before entering the value into the HP field for a more accurate Defensive CR. This calculator does not automate that step; you must pre-adjust the HP.
What is the maximum CR this calculator supports?
The calculator uses the official CR chart values from CR 0 up to CR 10, covering most common monsters. While the official chart extends to CR 30, higher CRs require more complex analysis of legendary actions and saving throw DCs which are outside the scope of this simplified tool.
Do I include legendary actions in the DPR calculation?
Yes. When calculating Damage Per Round (DPR), you must include the damage contribution from legendary actions spread over a three-round combat scenario, in addition to standard actions and bonus actions. The calculation should reflect the creature’s true average damage output.
Can I use fractional values for HP or DPR?
The inputs are designed for whole numbers (integers), as most D&D statistics are presented this way. If your calculated average DPR is a decimal (e.g., 20.5), it is generally best practice to round to the nearest whole number before inputting it into the calculator.