Generally you need around a 2 to 1 ratio whenever you're converting from one "input" good to an "output" good. It's actually more like 5 to 3 (give or take) in practice.
If the production chain has several steps, you'll need 2x the number of inputs at each level. For instance, if good A requires good B, and good B requires good C, you'll need:
- 4 good C production buildings in order to supply
- 2 good B production buildings in order to supply
- 1 good A production building.
At 2 good A production buildings though, you might only need 6 or so good C production buildings. Some of this also depends on the characteristics of the location for certain "input" goods.
There is some variance from good to good, so what I generally do is build 2 of the "input" production buildings per 1 "output" production building, and then as the industry grows (ie, I have 5 or 6 "input" production buildings) I keep a close eye on whether or not the "input" good is being stockpiled or is the limiting factor in production.
Since there are a lot of variables (ie, time to collect the good and move it from place to place), each industry differs slightly, and the math doesn't tend to work out evenly, there's not a catch-all rule you can use. As you encounter new production chains, you'll have to do some monitoring to work out the best ratio.