The Robot Factory, also known as Robo or Robo Factory, increases the speed at which buildings are constructed on the respective planet or moon. However, it does not affect the construction of ships and defensive structures. In the later stages of the game, the construction time of buildings can be further reduced by the Nanite Factory.

To calculate how the construction time reduction of buildings per level of the Robot Factory affects, there are the following formulas:

Construction time = ([[Metall|Metal]] + [[Kristall|Crystal]]) / (2500 * (1 + Robot Factory Level) * 2 ^ "Level [[Nanitenfabrik|Nanite Factory]])

The new construction time with an upgrade of the Robot Factory by one level is:

Construction time = "Previous Construction Time" - "Previous Construction Time" / (1 + new Robot Factory Level)

In general, when upgrading the Robot Factory:

Construction time = "Previous Construction Time" * (1 + old Robot Factory Level) / (1 + new Robot Factory Level)

Attention

The higher the Robot Factory is upgraded, the more the effective construction time reduction decreases. Therefore, after upgrading to level 10, it is better to prioritize the Nanite Factory, as it accelerates both construction of buildings and production of defensive and ship units, much more drastically than a further level of the Robot Factory with comparatively less space requirement.

Unlike the Nanite Factory, the Robot Factory can also be built on a moon and significantly reduces the construction time of the Jump Gate. However, it should also be mentioned that upgrading the Robot Factory beyond level 10 is not generally pointless. This is most evident when the Nanite Factory is to be upgraded. The construction time always remains the same as long as the Robot Factory is not upgraded.

Example:
Robot Factory Level 10 = Construction time for [[Nanitenfabrik|Nanite Factory]] 2d 6h 32m 43s
Robot Factory Level 11 = Construction time for [[Nanitenfabrik|Nanite Factory]] 2d 2h 0m

This corresponds to a time saving of 4h 32m 43s for the cost of 409,600 Metal, 122,800 Crystal, 204,800 Deuterium. However, it should be considered that upgrading the 
Robot Factory to level 11 also takes 19h 21m 46s, assuming no Nanite Factory is present. Otherwise, the construction time 
of the Robot Factory is halved for each upgraded level of the Nanite Factory. (Example at Nanite level 1, upgrading Robo to 11: 9h 40min 53s)

The same time saving also applies to all other buildings. However, whether the additional resource costs and fields are worth it, each player must decide for themselves.
If space is not an issue, upgrading the Robot Factory can again be the more cost-effective alternative from a certain level of the Nanite Factory.
This case first occurs from Nanite Factory level 3. In terms of standard metal units, a Robot Factory level 11 costs 1.27 million MSE.
A Nanite Factory level 3 costs 9.2 million MSE. The Robot Factory offers a construction time reduction of 8.3%, i.e. 1% time reduction 152,983.13 MSE, the 
Nanite Factory offers a reduction of 50%, 1% time reduction costs 184,000 MSE.
The Robot Factory is thus the more cost-effective solution, but with the disadvantage of additional space requirement and the fact that its upgrade does not affect spaceship production unlike
the Nanite Factory. The next break-even point is at Nanite Factory 4, cost-wise the Robot Factory level 12 is again superior (cost 
per 1% time reduction: 329,807.79 MSE vs. 368,000 MSE). Similarly, the Robot Factory level 13 is relatively cheaper compared to Nanite Factory level 5.

For illustration of the construction time reduction, here is a corresponding table: