How big is Bahamut?

[axemtitanium]

I was curious about just how big Bahamut is. Inspired by xkcd, I will use Fermi estimation to calculate a ballpark guess for how large the elder primal is.

Assumptions:

1. Hydaelyn is a roughly Earth-sized planet. Mean radius = 6371 km.
2. Menphina is a roughly Moon-sized natural satellite. Mean radius = 1737 km.
3. Dalamud is roughly as small compared to Menphina as the Moon is to Earth.*
4. Bahamut's wingspan is roughly twice the diameter of Dalamud, according to the End of an Era trailer.
5. Bahamut's height is about 1/3 the length of one wing.

*This is the most difficult assumption because there is no accurate way to estimate the size of Dalamud from a land-based observer. Twin moon systems like Menphina and Dalamud are exceedingly rare in nature so it's challenging to find a good estimate of what counts as "reasonable" or "reasonably possible".

Given these assumptions, let's crunch some numbers.

• 1737 km radius of Moon / 6371 km radius of Earth = 0.2726; the Moon is roughly 1/4 the radius of the Earth
• 1/4 * 1737 km radius of Moon = 434.25 km; Dalamud is just over 400 km in radius
• 400 km radius of Dalamud * 2 (for diameter) * 2 (for double diameter) = 1600 km; Bahamut's wingspan is about 1600 km
• 1600 km wingspan * 1/2 (one wing) * 1/3 = 267 km height

For reference, 1600 km is about the same distance from Berlin to Moscow (alternatively, about half the distance between Washington, DC and Los Angeles). Eorzea has been compared to the size of Europe so I'd guesstimate this to be around the same distance between Limsa Lominsa and Gridania. In other words, Bahamut is really frickin' big. Even with a conservative Fermi estimate, Bahamut's wingspan would still be on the order of 1000 km (3 orders of magnitude). At 267 km, Bahamut is as tall as the state of Pennsylvania (longitudinally).

This is larger than any dragon we've ever seen before in the entire game. His father, Midgardsormr, is only about as massive as the Agrius airship, which can't be larger than an aircraft carrier. There are a few things that could account for this. First, my assumptions could be way off. Hydaelyn could be a much smaller planet; Menphina could be a much smaller moon; and Dalamud could be a much smaller satellite. There's really no way to tell. The only shot we've seen of the planet is this one:

Eorzea looks relatively Europe-sized, compared to the planet as a whole. That said, even if Hydaelyn were smaller than Earth, the proportion should still stay the same (i.e. his wingspan goes from Limsa to Gridania), unless that ratio is also way off. Bahamut the primal could also be much huger because of his status as a primal, whose power level corresponds to the amount of prayer and aether he's absorbed. As an elder primal who has absorbed energy from the sun for multiple millennia, it's possible that Bahamut's size increased proportionately.

Finally, to any enterprising Fermi estimationists, there are two other ways that we might calculate the size of Bahamut, perhaps more accurately. One, you could compare the width of the Dalamud fragment that impacted Carteneau in the End of an Era trailer with the known approximate height of the soldiers who are helpfully included in the shot for comparison. Then from there, calculate the size of Dalamud in Dalamud fragment-widths. Alternatively, you could estimate based on the size of Bahamut's claw, the battle arena of T5. It should be possible to measure the width of his hand in yalms and then scale that up to the size of his body and wingspan using the proportions above. Good luck!

[Anonymoose]

Bahamut is perhaps still the biggest dragon we've seen so far, but Merlwyb off-handedly compares his size to being roughly the same as an Eorzean city (the whole thing, I imagine, not just the parts we can wander), so the size of Penn. as a whole seems to be much too much. The palm approach seems like a good idea, but keep in mind that proportion and scale aren't always first on the dev. team's priorities and it might not all line up right, lol.

EDIT: Found it

From inside the shell of Dalamud came a winged nightmare—a dragon the size of a bloody city.

[dvoraen]

Keep in mind that Bahamut may well have been artificially inflated in size. The Final Coil of Bahamut kind of implies this. I'd say the 'real' Bahamut would have been about the size of the large dragon we see in the Tour of the North video.

[Dererk]

Keep in mind that Bahamut may well have been artificially inflated in size. The Final Coil of Bahamut kind of implies this. I'd say the 'real' Bahamut would have been about the size of the large dragon we see in the Tour of the North video.

if your referring to T13 the burning heart no that is not his real size that is merely his essence on his crystal heart.

Also keep in mind Vishap wasn't even a great wyrm just a very big dragon now we take that into account and relies that Bahamut is one of the first broad the size of him being about the full size of Mor Dhona is about right. Also don't forget a primal to come into being needs 3 things crystals prayers and a mass of Athear now if we take into account the whole Dragons of Meracidia into account that is enough to summon a big entity it took the whole realm of Eorzea to summon the Twelve in Cartano to attempt to seal him.

[Cherub]

I'll allow myself to throw in my thoughts really quick. There is one thing I've been always wondering about. As we know Bahamut is a primal but there is the question of was he ever a dragon (and dragon only) or born a primal and if so, does him being a dragon (and dragon only) or being a primal change his size? not to mention how he became a primal but that's too crazy for me. Who knows maybe he isn't a primal after all. Maybe a crazy lalafell was the real bahamut.
We all know who phoenix is by now and mutation/transformation/power-uppu seems not out of question.
I can't really help out with the actual size guessing though but my 2 cents.

[treuhavik]

was he ever a dragon (and dragon only)

Yes.

does him being a dragon (and dragon only) or being a primal change his size?

We don't have hard information on this (primal inflation), but I'm 99.99% sure this is a "Yes" as well.

Midgardsormr's children are definitely larger than most dragons we will encounter

I'd hesitate to say anything definitively just yet, but Midgardsormr is likely slightly larger than his children and they all comparable in size to eachother. I also suspect that Vishap is much, much larger than the Dragons Seven based on the origin of his name.

[Cherub]

Yes.

I guess me wondering how he became a primal always lets me forget bout this fact.

We don't have hard information on this (primal inflation), but I'm 99.99% sure this is a "Yes" as well.

I wholeheartedly agree.

[Kaiser-Ace]

Based on my own estimates, Dalumuld is not nearly as big as some have guessed. It was barely a speck in the sky before 1.2 started it's decent.

From what I remember, dalumuld was probably several miles in diameter, (Earth's moon is about 2150 miles in diameter), thus making Dalamuld the approximate size of the Cretaceous Asteroid credited with the Dinosaur's Extinction.

Bahamut was at the center of this thing and bust out of it like it was an egg. From how we see him being sealed in the attempted new Dalamud his actual "Shell" was about 1/3 the diameter of the actual satellite.

So it's much more likely that his wingspan was about a mile or two give or take. Miles and Malms are interchangeable and the City States themselves are not actually that large. (Still the idea of a dragon with a over mile long wingspan is terrifying, especially when it's burning everything in it's path to ashes)

So it's likely his size in the Binding Coils IS how big he was upon his jail break at Cartenoue. And that "Bahamut Prime" was his original incarnation as a mortal Dragon. (Being much smaller and comparable in size to twintania from T5)

[Ashkendor]

As we know Bahamut is a primal but there is the question of was he ever a dragon (and dragon only)

Yes. He was one of the first brood (I'm assuming that makes him one of Midgardsormr's children); the Meracydians prayed to him and gave him new form as a primal. The Allagans kept countless dragons captive and tortured them so their constant cries for help would keep him from returning to the aether, therefore allowing them to imprison him in Dalamud.

All in all, it's truly a sad story. Bahamut has all the reason in the world to be exceedingly pissed off; the problem is that his rage is misplaced by the span of hundreds of years. Personally, I saw killing him as freeing a completely mad creature from the grip of his own rage-induced insanity. We did him a service as much as we did Eorzea.

[Velox]

If you watch the end of an era video, you can see Bahamut briefly against the Limsa Lominsa backdrop. He is roughly right above the city, so using this as a scale it definitely supports the claims (and from what we saw in the Coils) that he is as big or slightly bigger than most Eorzean cities head-to-tail. Wingspan is much larger. Overall, he's monstrous in size.

Bahamut in life may have been much smaller. Remember that the primal-version is represented as how the Mercydian dragons imagined him (as is with all primals). It's true that Midgardsormr's children are definitely larger than most dragons we will encounter, but Bahamut's sheer size may only be due to the fact that he was reincarnated as a primal. Likewise, he may have always been unnaturally big. 3.0 should give us more story into the origins of dragon-kind and how they all relate to each other.