Average Monster Stats in the 5e Starter Set

So I collected info from the 5e starter set's Bestiary to work out the average stats of a monster of a given CR. This should be helpful for creating monsters for a 5e game, or else to help convert monsters from other systems. I think you'll find that conversion is more a question of recreation and has more to do with concept than transferring crunch.

This might be a little spoilery as it lists all the creatures in the 5e starter set. It's also fucking gibberish to someone without a solid grasp of the rules.

Values in italics are estimated for lack of data.

Base Combat Values

To-hit modifiers were not included because there's not a whole lot of variation. They range from +2 to +7 and average around +4. Goblins get a +4 to hit, Orcs get a +5, Ogres get a +6. So that tells you something.

CR 1/8 (Cultist, Stirge, Twig Blight)
HP 5, HD 1.5, dmg 4

CR 1/4 (Goblin, Skeleton, Wolf, Zombie)
HP 10, HD 2, dmg 5

CR 1/2 (Hobgoblin, Orc, Bandit)
HP 15, HD 2, dmg 7, 

CR 1 (Bugbear,  Evil Mage, Ghoul, Giant Spider, NPC Warrior)
HP 25, HD 5, dmg 8

CR 2 (Grick, 4^th-level Wizard, Nothic, Ochre Jelly, Ogre)
HP 35, HD 6, dmg 10 – sometimes 2 attacks

CR 3 (Doppelganger, Wraith, Owlbear, Spectator)
HP 50, HD 7, dmg 15 – sometimes 2 attacks

CR 4 (Flameskull)
HP 70, dmg 17

CR 5
HP 85, dmg 19

CR 6
HP 100, dmg 21

CR 7
HP 120, dmg 23

CR 8 (Young Green Dragon)
HP 135, HD 20, dmg 26

Damage calculation for multiple attacks: Creatures with multiple attacks are assumed to do average damage for their first attack, and half average damage for subsequent attacks. (This is to factor in the possibility of hitting with one attack but not the other.)

Hit Die Type by Size

Hit die type appears, without exception, to be tied to size. This is even the case with classed NPCs: NPC mages use d8s, as do fighters. As far as I can tell, large monsters will sometimes have fewer HD to keep their HP appropriate to CR. This doesn't appear to the be the case for smaller creatures, however.

HD and size correspond as follows:

Tiny: d4

Small: d6

Medium: d8

Large: d10

Huge: d12?

Also note that HP values varied rather widely as of CR 2 or so. This is accounted for somewhat by the fact that creatures factor their Con modifier into every hit die - so a 7 HD monster with a Con score of 16 has an extra 21 hp on a 7 HD creature with Con 10.

Miscellaneous Crunch

Proficiency Bonus: Monsters have proficiency bonus factored into their math. However, it scales with Challenge Rating rather than HD - at least as far as I can tell. Every creature in the starter set bestiary has a +2 (even monsters with 6 or 7 HD, well into +3 territory for a PC) -- except for the Young Green Dragon, which has a +3, and is also the only creature with a CR greater than 4. An 8 HD PC has a +3 proficiency bonus, so proficiency-by-CR seems like the best bet.

Saves: Many creatures do not apply proficiency to any of their saves. Classed NPCs (NPC Fighter and 4th-level Wizard) have saves according to their class, and the Young Green Dragon has hella saves, but otherwise that's pretty much it. (The zombie has proficiency to Wisdom saves for reason??)

Skills: Many monsters don't have skills. When they do, it's usually pretty integral to their concept: Goblins and spiders have Stealth; Wolves has Stealth and Perception; some more majicky intelligent creatures have Arcana.

Some creatures even have double their proficiency bonus on certains kills as per a rogue's Expertise feature. The goblin, for example, has a +6 to stealth, despite having a +2 Dex modifier and a +2 proficiency bonus - so it would appear it gets double proficiency on those rolls.

Nonproficiency on Secondary Attacks: The ghoul applies its proficiency bonus with its claws but not its bite, which would suggest that it is not considered to be proficient with bite attacks. So that's a thing. As far as I can tell the ghoul is the only monster where this is the case.

Ability Scores: Ranged pretty widely according to monster concept. They rarely went higher than 16 (although the Owlbear does have 20 Strength, and the Young Green Dragon's lowest ability score is 12, its highest is 19). I tried to calculate average ability score modifier per CR but the numbers came up nonsense. These seem more an art than a science.

So here's how I would make a monster for 5e

1. Come up with a monster.
2. Determine CR. It seems to me like a CR 1 monster poses a serious but survivable challenge for a group of 3-5 well-prepared PCs of level 1. Someone who's played more can probably tell you more about this. This will give you the creature's proficiency bonus, where CR = effective PC level.
3. Assign Ability Scores. Whatever feels right, keeping in mind that 10 average and 20 represents the absolute peak of human capacity.
4. Determine size. This will determine the monster's HD type.
5. Determine number of HD. This should usually be the average for a creature of this CR. Large creatures might have fewer to keep HP reasonable, and creatures with extraordinary powers might also have fewer. If it's supposed to be like a tank, give it a couple extra.
6. Give it attacks and powers. For attacks I'd use average damage per CR as a guideline. Use ability scores and proficiency bonus to calculate to-hit bonus.
7. Assign skills and saves. This is really according to concept. If a skill seems really important, give it expertise.
8. Ok done.