Fabbers…how many to build and when

I go 2-3 bot fabbers at the beginning. Then if a fabber dies I ctrl-click a replacement. I usually build 2 bot, then an air factory, then lots of vehicles(4-8), and eventually more bots. After I have the air factory, if I lose a bot fabber I sometimes replace with an air fabber because if they dont' have strong air I can protect him better and get to random places faster.

Most of the times I go 2 factories first, 2 fabbers in first one, one in another. Sometimes if planet is a bigger one and metal rich, I can do 4 or 5, and if planet is small and has little metal, I'll only make 2. But normally it's 3. Usually 2 fabbers building mex (together, not in different spots) with some dox escort, and another one dropping a radar and then either non-stop power, or more likely, assisting commander (which means power mixed with factories). If radar detects any enemies really close, I am usually redoing queue for mex fabbers, so they are not in danger.

The rest depends on situation, i.e. enemies around and what they are doing. Most of the time I produce two more fabbers from fourth factory. What comes after this is never the same.

It's not the best build, but very easy to learn and manage. Initially, you only have a pair of fabbers outside your base at the same spot, protected with doxen from random encounters. Another fabber is at your base. I don't usually lose fabbers at start, unless my opponent is hardcore, or I failed at executing my own build order (no escort or radar or not enough power for radar). So, yeah, it's easy general build.

On larger maps, I'll just set my first factory to infinite-build and have it churning out fabbers permanently. Logic here is, your enemy probably isn't near enough to insta-rush you - and if radar shows he is, instead I'll churn out 5 fabbers and put out a slew of tanks instead.

It's kind of dependent on what sort of situation you're in.

Dont forget that in 1v1 its still viable to go 0 fabricators. Just build a shitload of factorys with your commander and trash everything you see. Its not easy but i would prefer 0 fabricator start over the endless engineer start on normal 1v1 maps.

Agaisnt normal (and usualyl also hard) AI, this is the start I most often use:
https://forums.uberent.com/threads/how-to-beat-normal-ai.64357/

With PvP other rules apply.
Generally you want to have enough fabbers and factories that you can use up to 100% of your metal income (with some peak during building).
So the big question is: How many mex spots do you have to feed those fabbers/factories?

Fixed that for you.

1 or 3 fabbers are ideal, map size and biome dependant. Pretty much is down to your gamestyle and how you like to attack. 3 fabber start on small map is more passive and most your early game units are protecting your 2 expansions. 1 fabber player has good early timings to attack your fabbers with all his units.

I tend to start one as I'm pretty confident I can harass a 3 fabber start player good enough to apply pressure and build my fabbers a little later if needed.

Yeah 1 fabricator starts seem pretty powerfull