D&D 5E (2014) Your CR limit for an average 1st level party?

[Plaguescarred]

CR 2-3 depending on the monster's output and forgiving tactic used.

 

[Weiley31]

Didn't Icespire Peak send first level PCs against a manticore?

It did, but it also allowed you an "out" option to the fight by being able to convince it to move somewhere else instead IIRC.

 

[UngeheuerLich]

CR3 is swingy. That is the biggest problem. Some creatures can't do anything if you can keep them at distance. Or disabled.
In 5.5e everyone either has cantrips or weapon masteries and one extra feat. Those are game changers. This enables them to have a chance against a CR3 monster.

But what people said:
I think there should be no party vs 1 cr 3 monster fight. Better use a CR 1 and some minions of CR 1/8 or 1/4. Or CR2 and one minion of CR 1/4. This will mame the fight a little bit less swingy.

Or as othe people said:
Give your players a level up. The change from level 1 to 2 usually has no big additional choices except or a few extra level 1 spells or invocations. No choice of subclass.
At level 2 we look at 4 to 10 extra hp. Which means a lot more distance to insta kill. A CR 3 monster gets manageable.

 

[greymist]

I agree with Ungeheuer Lich. A CR 1 boss with some lower CR helpers.

I give m PCs extra HP at lower levels, but I also increase the XP requirements to reach Levels 2 and 3.

 

[Cap'n Kobold]

Never assume that a low-level PC will make any save.
Never assume that a PC will be at full health.

Anything able to deal 10 or more points of damage in a single go can outright kill a PC, and there are no options to bring them back at this level.

Creatures that rely on multiple attacks are safer because you can always go for another PC if you drop one. Or just use more enemies rather than relying on high-CR ones.

Or use enemies that are defeated outside of combat, through puzzles or the like. Fey creatures setting riddles for example.