Green science is the wall that separates casual manual-crafting from real automation. Unlike red science (two ingredients, one assembler, done), green science forces you to think about sub-factories, belt balancing, and ratios. I've rebuilt this thing a dozen times across different playthroughs, and every time I find a cleaner way to lay it out.
Recipe
Each logistic science pack takes two items. Here's the exact recipe chain:
Inserter
Transport belt
Logistic scienceThe inserter recipe itself needs iron gears, green circuits, and iron plates. The belt recipe needs just one iron plate. So the full chain from raw materials is:
Iron plate
Circuit green
Iron gearRatio Math — Getting the Numbers Right
Here's the math after crunching it:
| Machine | Output | Needed assemblers | Feeds how many science asm |
|---|---|---|---|
| Green science assembler | 1 pack / 6s | 10 | — |
| Inserter assembler | 1 inserter / 0.5s | 1 | Up to 12 science assemblers |
| Belt assembler | 2 belts / 0.5s | 1 | Up to 24 science assemblers |
| Green circuit assembler | 1 circuit / 0.5s | 1 | Shared with red science |
The ratio is forgiving: one inserter assembler makes 2 inserters per second. Each science assembler eats 1 inserter every 6 seconds, so a single inserter assembler supports 12 science assemblers. Belt assemblers are even more efficient — 4 belts per second feeding 24 science assemblers.
Bottom line: Build 1 inserter assembler, 1 belt assembler, and 10 green science assemblers. It's a clean ratio that works from your first build through the mid-game.
Layout That Works Every Time
I've tried a few layouts. The one that sticks is a straight-line double-sided build with components running down the middle:
Put inserter and belt assemblers in a row. Iron plates on one belt lane, green circuits on the other. Science packs go to a third belt feeding labs.
Integrating Into Your Factory
Green science is when you need a proper bus. Here's the minimum belt setup near labs:
- Iron plates — one full belt lane
- Copper plates — one lane for circuit production
- Green circuits — already made for red science, just extend the belt
- Green science output — dedicated belt feeding labs
Don't bother with a separate iron gear belt. A single gear assembler (steel furnace fed) handles everything up to blue science.
Mistakes I Kept Making
The belt backup trap. I once spent an hour debugging why inserters weren't working. Turned out the green science belt was full — inserters couldn't place packs, which caused inserter production to back up. Solution: more labs or a buffer chest.
Not enough copper wire. One copper wire assembler feeds about 6 green circuit assemblers. If circuit production stalls, wire is almost always the culprit.
Forgetting the output inserter. Done this more times than I'd like to admit. Assembler fills up with science packs, no way out. Always put a fast inserter on output.
Scaling for Early Game
Once you unlock Assembler 2 and fast belts, scaling is straightforward:
- Upgrade belts on the bus
- Switch science assemblers to Assembler 2
- Add a second inserter+belt assembler if pushing 30+ green SPM
- Red inserters speed up throughput
Bottom Line
Green science is the first test of real factory design. Get this ratio once, and you won't touch it again until megabase territory.
Numbers to remember:
- One inserter + one belt assembler feeds 10 green science assemblers
- One green circuit assembler handles both red and green at this scale
- One iron plate belt lane supports everything
Next up: The Blue Science Guide — oil processing is where Factorio really starts.