Where should i used my productivity modules?

[IAN]

Assuming i have a finite amount, In terms of priority how should i use the modules first?

[KatherineOfSky]

Think about where they would give you the most benefit... labs or the rocket silo first, since those "free" materials from the modules represent a huge amount of materials/manufacturing.

[Ruges]

Simple answer is last item in the chain. Since it affects every item that comes before it (some of which cannot use prod modules). And it takes more items to make less items (IE to make Item D in one factory. you need 2 factories producing item C. Item C needs 4 factories of item B. and Item B needs 8 factories of item A.) Puting 4 prod modules into factory D would be the same as putting 32 prod modules into factory A.

[IAN]

Very good answer guys, yes I think labs and rockets is it.

[Magic]

Red and blue chips are a good place too.
2 productivity and one speed give you some extra circuits without loss of production speed

[Stryke(r)]

Just keep in mind, that the bonus progress resets every time you change research (so try to avoid that)

[Teh Freek]

https://www.reddit.com/r/factorio/comments/68szo3/what_to_productivity_module_first_in_015/

[Name Lips]

I like to use them on things higher up the production lines (like blue chips) because, effectively, it's a bonus to all the resources going into making them.

If you get 20% productivity in an iron furnace, for instance, you'll get 20% more iron plates for free.

If you put it in a blue circuit assembler, you get (effectively) a 20% bonus to all the ingredients going into the circuits -- which are 40 copper plates, 24 iron plates, 4 plastic bars, and 5 sulfuric acid.

This is a particular benefit because blue circuits are used to make more productivity modules.

Ultimately though it'll depend on your factory... there's not much point in putting productivity into things that you're already making so many of that you have a huge backlog. You can use them to fix bottlenecks in your production line.

[Warlord]

I tend to use it in Oil Processing. Since oil goes up and down so much, and oil fields deplete rather fast, I stick them into refineries and just double up on them. Saves a lot on coal (liquifaction) and oil (adv. processing). If I feel like it, I can also use it in the byproducts, such as lubricant, crackers, plastics, acid, and solid/focket fuel.