D&D Challenge Rating (CR) Estimator
Estimate a monster's Challenge Rating in D&D 5e from its HP, AC, attack bonus, and average damage per round.
Includes CR-to-XP reference table.
What Is Challenge Rating?
Challenge Rating (CR) is D&D 5e’s difficulty label for monsters. A monster of CR X is designed to be a medium difficulty fight for a party of four level-X characters. CR also determines the XP reward the party earns after the encounter.
How CR Is Calculated
The Dungeon Master’s Guide uses a two-part approach:
- Defensive CR, estimated from the monster’s HP and AC
- Offensive CR, estimated from the monster’s attack bonus and average damage per round
- Final CR = average of the two
HP to Defensive CR (Baseline)
One rough way: divide HP by 12 to get a baseline defensive CR. The monster’s AC is then compared to the “expected AC” for that CR to adjust up or down.
| CR | Expected HP | Expected AC | Attack | Damage/Round | XP |
|---|---|---|---|---|---|
| 0 | 1–6 | 13 | +3 | 0–1 | 10 |
| 1/8 | 7–35 | 13 | +3 | 2–3 | 25 |
| 1/4 | 36–49 | 13 | +3 | 4–5 | 50 |
| 1/2 | 50–70 | 13 | +3 | 6–8 | 100 |
| 1 | 71–85 | 13 | +3 | 9–14 | 200 |
| 2 | 86–100 | 13 | +3 | 15–20 | 450 |
| 3 | 101–115 | 13 | +4 | 21–26 | 700 |
| 4 | 116–130 | 14 | +5 | 27–32 | 1,100 |
| 5 | 131–145 | 15 | +6 | 33–38 | 1,800 |
| 6 | 146–160 | 15 | +6 | 39–44 | 2,300 |
| 7 | 161–175 | 15 | +6 | 45–50 | 2,900 |
| 8 | 176–190 | 16 | +7 | 51–56 | 3,900 |
| 9 | 191–205 | 16 | +7 | 57–62 | 5,000 |
| 10 | 206–220 | 17 | +7 | 63–68 | 5,900 |
| 11 | 221–235 | 17 | +8 | 69–74 | 7,200 |
| 12 | 236–250 | 17 | +8 | 75–80 | 8,400 |
| 13 | 251–265 | 18 | +8 | 81–86 | 10,000 |
| 14 | 266–280 | 18 | +8 | 87–92 | 11,500 |
| 15 | 281–295 | 18 | +8 | 93–98 | 13,000 |
| 16 | 296–310 | 18 | +9 | 99–104 | 15,000 |
| 17 | 311–325 | 19 | +10 | 105–110 | 18,000 |
| 18 | 326–340 | 19 | +10 | 111–116 | 20,000 |
| 19 | 341–355 | 19 | +10 | 117–122 | 22,000 |
| 20 | 356–400 | 19 | +10 | 123–140 | 25,000 |
How the two adjustments work
Hit points give you a starting row, then armor class corrects it. Every 2 points your monster’s AC sits above or below the expected AC for that row moves it one row, up or down. The damage side works the same way against the expected attack bonus. Average the two adjusted rows and you have the final CR.
A worked case. A monster with 178 HP starts at CR 9. Give it AC 18 against an expected 16, which is 2 points high, so it moves up one row to CR 10. Now 66 damage a round puts it at CR 11 offensively, and a +10 attack against an expected +8 pushes that to CR 12. Average CR 10 and CR 12 and you land on CR 11.
The real answer for that statblock, a young red dragon, is CR 10. Being one step out is normal and the DMG says so.
Where this estimate goes wrong
The formula only sees four numbers, and four numbers do not describe a monster. Legendary actions and legendary resistance are the big omissions: a creature that shrugs off three failed saves per day and acts on other people’s turns is far more dangerous than its damage output suggests, and the DMG tells you to bump CR for them by hand. Flight against a party with no ranged options, pack tactics, a paralysing bite, or a recharge breath weapon that lands 60 damage on four people at once all break the model in the same direction. Resistances and immunities matter too. A creature immune to nonmagical weapons is unkillable at low levels and ordinary at high ones, and CR cannot express that.
Treat the output as the floor of the fight’s real difficulty, then playtest it.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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