[PF] Guideline for Summon Monster spell

[Maquise]

I was looking at the Summon Monster (http://www.d20pfsrd.com/magic/all-spells/s/summon-monster) entry at d20pfsrd.com, and noticed it was not up to date; several demons and such from the newer bestiaries were not listed in the entries of monsters you can summon.

As far as I could tell, the general guideline seemed to be that the level of spell you needed was equal to the creature's CR - 1. Is this accurate?

EDIT: Just to be clear, I am the GM in the game this applies to.

[SamBurke]

I was looking at the Summon Monster (http://www.d20pfsrd.com/magic/all-spells/s/summon-monster) entry at d20pfsrd.com, and noticed it was not up to date; several demons and such from the newer bestiaries were not listed in the entries of monsters you can summon.

As far as I could tell, the general guideline seemed to be that the level of spell you needed was equal to the creature's CR - 1. Is this accurate?

EDIT: Just to be clear, I am the GM in the game this applies to.

That's roughly correct, though sometimes it may be CR -2.

[Maquise]

Is there any real way to know what level a particular creature fits? As in, would it in fact be CR - 2?

[TheArsenal]

Well some monsters are CR 11 or 13 at summon monster 9.