Ottoman Imperial observatory math breakdown

Gonna explain the formula behind the train time modification. Math first, with and whiteout fast training, then the application of the imperial observatory and conversion to res gain.

I found out that the train time is multiplied by the reciprocal of the production bonus; 40% faster production means you multiply the base time by (1 / 1.4) = 0.71.

  • e.g Lancer base time = 156 sec, at age 4 reduced to 156 * 0.71= 110.76 sec.

The Faster Training vizier tech adjusts the base training time directly, before the influence bonus applies so thats another amplification effect.

  • e.g Lancer base time = 156 sec, new base time with FT = 156 * (1/1.25) = 124.8 sec, at age 4 reduced to = 124.8 * 0.71 = 89 sec.

A short way to get the total train time reduction is to multiply the reciprocals;

  • 1/1.25 * 1/1.4 = 0.57.

That means that at age 4, with FT, units take 57% of the base train time.

Imperial Observatory boost of 20% stacks additively with the base production bonus (1.4 + 0.2 = 1.6). Applying the same process above, Imperial Observatory alone means a train time multiplier of x0.625, and with FT the multiplier becomes x0.5. (Lancer goes from 156 sec to 78 sec)

The eco value varies with the type of unit produced. Infantry units tend to give the least value with lancers giving the most for a range of 143 - 185 res/ min per military school. With 5 running that amounts to 715 - 925 res/min.

Assuming you skipped the Imperial Observatory for the sweet, sweet gold income then the numbers go down to 125 - 162 res/min per military school (625 - 810 res/min). The total effect of the Imperial Observatory is about +15% more equivalent res generated.

Personally, I’d take the Sea Gate Castle for the +30% trade income as a no brainer option, since that’s actual gold that I can covert to other res later on. Any thoughts on this landmark?


Well the Observatory bonus just happens automatically whereas the sea gate castle requires you to set up trade and, if you want to maximize it, build some keeps as well.

So I’d expect the raw numbers to be better for the Seagate than the Observatory since it has a higher barrier to achieve that value.

I think you’re missing one factor, the Mehmed Imperial Armory landmark.

This is kind of a highly enhanced Military Schools. Furthermore, the increase in training speed is significant for the strength increase in long seesaw battles, which is an global bonus. Will make your reinforcements faster to reach the battlefield, keeping you always had the advantage of numbers, resulting in qualitative change.


Yea, I was gonna add the Mehmet Imp Armory and while that does at ALOT of value to the overall Otto military machine, it didnt actually change the overall gain of 13-15% res/min from the Imp Observatory. Plus, you can take that independent of whichever age 4 landmark you decide to take and then it circles back to the same decision - sea gate for absolute income or observatory for easy macro.

And that goes into a new discussion of what the win conditions are in the match/map and weather I can actually macro that income into defenses or military. I personally try to plan ahead for age 4 and aim for a comp that can use the extra gold - for instance, ribauldequins are expensive and take way to long to reach critical mass form the armory but you can make them out the siege workshop easy once the trade is established. I pay for my siege to build it faster and let military schools build up my main army.


Its hard to guage the exact number since, in the end, sea gate is only as good as the number of traders you make. It fits my personal playstyle so I’m partial to the castle - the extra macro needed to manage the gold pays off pretty nicely when you need to buy stone in the lategame or need to remass an army faster than the military schools.

My conclusion is that, with practice, sea gate really outshines the observatory. If you think about it, is +13-15% res rate really a big spike for in imperial landmark if that’s all it offers?

Are we just gonna not talk about how it’s the Istanbul Observatory, not the Imperial Observatory?

…Well its not the Constantinople observatory. Whoops.