What is the biggest single damage number possible (no LB)

[AzumaKun]

That is a lie. I main bard but my Alt job at the moment is dragoon and i have hetroi armor and still only have af1 head and arms, with full DL accessories and i'm hitting about 1100 crits with blood for blood and lifesurge true thrust. The best geared dragoons hit much, much harder than that. How would a class built for single target burst damage hit just over 1k when my bard that has low potency attacks has the potential to crit for around 800....

No. Just, no. Critting for 1100? With that gear? No.
I have fullDL with AF2 and Allagan pieces mixed in, all bonus stats put into STR, and relic+1 and I'm critting for just under 1100 with FullThrust, B4B, HT, Disembowel, and Life Surge.

[Strength]

lies, lies everywhere!

[kasei]

If the max amount of damage isn't hardcoded as 9,999, then we have a serious problem.

[Ronzeru]

Depends on what mob you're fighting. I've hit over 1100. But regardless, what Azuma-kun said is pretty much right lol. You're barely gonna 'constantly' go over that, unless some serious other factors are involved.

[Shadowzanon]

2k in a span of 10 sec is easy to do as a blm. 4 fire spells in a span of 10 seconds. i can do from 2800 ish dmg if i dont crit at all or get firestarter (my balls of fire hit for about 700ish or so) to over 5k if 2 fire 1s crit (a bit over 1k) and i get 2 firestarter procs that crit (over 1500dmg) this is not including ranging strikes or if foe is aval.

[xyaie]

If the max amount of damage isn't hardcoded as 9,999, then we have a serious problem.

it isnt unfortunately i wanna say it was ifrit but one of the primals raged for like 14k

[Paikis]

MRD using Darklight and Titan's Axe. Butcher's Block crit for 1219.

This could be much larger with Allagan stuff.

[ReviiLagoon]

2000 Crit with Flare + Raging strikes on a Gaol during titan. Funny enough we didn't have any melee dps in that group, so a blm / smn used the lb, and the 2nd person who was gaoled got free.

[ColdestHeaven]

I think that BLM are meant to be the strongest. So yeah, if you want to see big numbers that is the class you are looking for. Dragoons have more survivability than them, though. From my humble/noob experience as DRG, I hit for over 1k of damage only once (although it wasn't luck, it just was hard for me to get the circumstances right) and I know that in order for that to happen I need:
Heavy Thrust, Blood for Blood, Disembowel, Life surge / Internal release, Power surge (if using Jump).
Now, I noticed none of us actually counted Power Surge+Jump as the strongest attack we possess. True, we have Full Thrust with 300 potency while Jump is only 200, but PS actually boosts it up to 300. If you remember that Jumps are not on global cooldown...well, that makes us capable of hitting theoretically speaking two times 300 in a matter of moments. One of them could not crit, but again it's a matter of circumstances. Not on par with BLM, but we can pull our weights.