TL;DR: I require help in converting D&D 4th Edition to 3.5 Edition. (It also couldn't hurt to be able to convert 3.5 to 4.0 too.)
(Slightly) longer version: mechanically, they're very different systems. CR and monster levels, for instance, mean analogous but very different things. A single CR m creature is a challenge for a party of four PCs of level m in 3.x; a level n creature is 1/4 of a level-appropriate challenge for four PCs of level n in 4e.
You could work out a ratio, but that wouldn't be very helpful--since in converting from 4e to 3.5 you're going to have to make a lot of additional decisions about things like hit dice and even monster type that will change the equation. Since there's no real guidelines for those either, you're going to have to feel them out.
Keep the flavor text, and throw out the mechanics. They don't play with one another.
Short version: you can't.
(Slightly) longer version: mechanically, they're very different systems. CR and monster levels, for instance, mean analogous but very different things. A single CR m creature is a challenge for a party of four PCs of level m in 3.x; a level n creature is 1/4 of a level-appropriate challenge for four PCs of level n in 4e.
You could work out a ratio, but that wouldn't be very helpful--since in converting from 4e to 3.5 you're going to have to make a lot of additional decisions about things like hit dice and even monster type that will change the equation. Since there's no real guidelines for those either, you're going to have to feel them out.
Keep the flavor text, and throw out the mechanics. They don't play with one another.
Then this'll be interesting. I'm a perfectionist, so I don't want to goof up on, say, a conversion of a barlgura (sp?) and make it ridiculously overpowered, or so underpowered a gnoll could beat it with a stick until it disintigrates. Although, actually, a gnoll beating something to death with a stick is a tempting idea. I'll have to use that in a future adventure. Adding on to my first post, how would I be able to fit in the new artifact system from 4th edition into 3.5? It'd be interesting for a PC to find the Axe of the Dwarvish Lords, or the Hand of Vecna in a 3.5 campaign. Any thoughts on this too?
I was kinda curious to compare a 2e (my old edition) battle versus a 4e battle i.e. take 6 2e PCs and a group of monsters and compare to the equivalent in 4e.
Just haven't got round to it because it takes a long time to put 4e characters together.
Short version: you can't.
(Slightly) longer version: mechanically, they're very different systems. CR and monster levels, for instance, mean analogous but very different things. A single CR m creature is a challenge for a party of four PCs of level m in 3.x; a level n creature is 1/4 of a level-appropriate challenge for four PCs of level n in 4e.
You could work out a ratio, but that wouldn't be very helpful--since in converting from 4e to 3.5 you're going to have to make a lot of additional decisions about things like hit dice and even monster type that will change the equation. Since there's no real guidelines for those either, you're going to have to feel them out.
Keep the flavor text, and throw out the mechanics. They don't play with one another.
a level n creature in 4th edition gives exp equal to the amount it would take for an equal level PC to need exp*10 in order to gain a single level. Thus 4 level n creatures of the same level as the PCs are indeed going to be level appropriate for 4 characters. However, "level appropriate" as defined by each system is another matter.
You might take a look at how the offical peoples themselves convert things. I think there was a conversion one of them did a month or so ago that included monsters.
There must be some ratio of Armor Class, Hit Points based upon level that you can use.
I was kinda curious to compare a 2e (my old edition) battle versus a 4e battle i.e. take 6 2e PCs and a group of monsters and compare to the equivalent in 4e.
Just haven't got round to it because it takes a long time to put 4e characters together.
. . .Not that long. 30 minutes at least, sure. But maybe an hour on average. I've had video games whose intros/tutorial stages lasted longer than that.
Just... no guaruantees that the 3.5e statblocks will work in the adventure; sometimes the monsters are much higher or lower level in different versions.
There must be some ratio of Armor Class, Hit Points based upon level that you can use.
I was kinda curious to compare a 2e (my old edition) battle versus a 4e battle i.e. take 6 2e PCs and a group of monsters and compare to the equivalent in 4e.
Just haven't got round to it because it takes a long time to put 4e characters together.
I'd say (from personal experience) that the math behind 3e is a lot less "tight" in terms of what is appropriate for a specific level of a monster in terms of AC and to hit for instance.
The problem also is that in 3e the chance of hitting your enemies with your first attack are often very high (a high bab + good stat + bonuses) but your subsequent iterative attacks might miss it - the defense vs. offense system is fairly different in that sense.
The saves you could convert to 4e defenses and vice versa, but those are also going to be quite swingy in comparison.
I'd just take a few good ideas from a 4e monster in terms of powers and/or other stuff and port them to a typical 3e monster template. Don't try to convert the stat block each "field" at a time. For to hit numbers, use 3e values and for damage also look for a comparison, since hp and damage scale rather differently too. For something that targets non-AC defenses, you have to make a save DC, which is basically the to-hit number +10 and then you roll a save vs. that using the creatures save + d20 (e.g the 3e way).
Or as an alternative, why don't you just play 4e instead of the whole hassle?