D&D (2024) "Conversion" of Old Monsters to New Standards

[Retreater]

I'm fairly sure I saw a video from @SlyFlourish or maybe Teos Abadia (Alphastream) that had a guide of increasing monster HP to bring them more in line with the 2024/25 math. I think it was don't change low CR, double others, etc.

Has anyone seen this video or know what the conversion rate is?

(I'm wanting to use creatures from sources other than the Monster Manual and don't want to toss my old books.)

 

[DragonLancer]

Does the MM not have a conversion guide? I thought I read that it did or did I dream it?

 

[Stormonu]

Does the MM not have a conversion guide? I thought I read that it did or did I dream it?

It has a "use this in place of this" for certain humanoids, but I think what is desired is a "Creatures of this CR increase HP and damage by X% or <fixed number>"

One of the other threads around here was looking at the hp/damage across the new monsters - I think it was by @mearls .

 

[DragonLancer]

That must be what I was thinking of then. Thanks.

 

[Count_Zero]

I'd find this very useful, since I'm running Dragonlance, and having some help in adapting the various Draconians over would be helpful.

 

[SlyFlourish]

There are a couple of good analyses:

Monster Manual (2024)

A comprehensive breakdown of the 2024 Monster Manual.

tomedunn.github.io

2024 Monster Manual on a Business Card

(v2: edited 2/25/2025 to fix a data error for legendary monsters, read more here on that fix) The 2024 Monster Manual is out, so we can finally answer all the questions we have: are 2024 Monster Ma…

www.blogofholding.com

My easy rule of thumb is:

• AC / DC = 12 + 1/2 CR
• HP = 15 to 20 x CR
• Attack / Proficient Save = 3 + 1/2 CR
• Damage per Round = 7 x CR

That gets you pretty close for a quick improvised monster and they're all numbers you can generally keep in your head.

Scott Fitzgerald Gray, Teos Abadia, and I also came up with a monster stats by CR table after analyzing D&D 2014 and many of the monster books that came afterwards and bounced it against Paul Hughes's work for Level Up Advanced 5e. We published it in Forge of Foes and you can find it in our free and CC-released reference document here:

The Lazy GM's 5e Monster Builder Resource Document

Lazy GM guidelines for building and running 5th edition compatible monsters.

slyflourish.com

We didn't have D&D 2025 monster stats then but it's close enough for an improvised monster that I wouldn't worry about it.

 

[DarkCrisis]

I'd find this very useful, since I'm running Dragonlance, and having some help in adapting the various Draconians over would be helpful.

Me as well. I'd be interested in hearing what you come up with.

 

[dave2008]

Paul's analysis (that @SlyFlourish linked to above) has a really easy method to check / revise monster HP & damage. Two things to keep in mind per his analysis (and make sure to understand what it does and does not cover):

Hit Points are pretty similar until about CR 17 (CR 18 - 1 monster screws up the graph) and really about CR 20 when the jump higher.

Damage (DPR) jumps up almost from the get go, with a greater increase at higher CR:

 

[Lazybones]

My groups have five or six players and they are quite skilled with the game mechanics, so I'm used to having to upgrade monsters a bit already. I am currently running one 2024 game that I built using the 2014 Monster Manual and I haven't noticed any issues, but it's pretty low-level at the moment. I'll probably swap in 2024 creatures as I go.

 

[dave2008]

I'd find this very useful, since I'm running Dragonlance, and having some help in adapting the various Draconians over would be helpful.

The draconians (IIRC) are low enough CR that it will not make to much of a difference. The big changes happen at CR17+. However, you could raise damage by about 50% and be OK per Paul's analysis