Key Ratios
The handful of community ratios worth memorizing: smelting, mining, science assemblers, and oil cracking. Verify any exact build against a calculator.
At a glance
| Why ratios matter | Factorio is partly a math game. A balanced line never starves and never backs up. |
| The big caveat | Module tiers, mining productivity research, and assembler tier all shift the numbers. Treat these as starting points, not laws. |
| The one rule | Feed the front of the chain first. A perfect assembler ratio is useless if ore never arrives. |
Verify any exact count against an in-game or online calculator before you commit to a large build. The figures below are sourced ratios, not universal constants.
Smelting (ore to plates)
A stone furnace smelts one ore in 3.2 seconds. Steel and electric furnaces do it in 1.6 seconds, twice as fast. To saturate one yellow belt of plates (15 per second):
| Furnace type | Furnaces per yellow belt |
|---|---|
| Stone | 48 |
| Steel or electric | 24 |
A full red belt of plates needs about 48 steel or electric furnaces. A full blue belt (about 40 ore per second) needs roughly 72.
Mining (drills per belt)
Without mining productivity research, saturating a belt of ore takes:
| Belt | Electric mining drills |
|---|---|
| Yellow | about 30 (15 per side) |
| Red | about 60 |
| Blue | about 90 |
Science pack assemblers
The wiki gives one combined ratio to keep all six base packs producing in sync with a single assembler tier across the board:
5 : 6 : 5 : 12 : 7 : 7 (automation : logistic : military : chemical : production : utility). With assembling machine 3s, that produces 75 packs per minute.
A simpler beginner ratio: 10 red assemblers to 12 green makes exactly 1 of each per second.
The Space Age ratio (factoring in foundry and electromagnetic-plant productivity, agricultural science at full freshness) is 3 : 6.67 : 6.67 : 4 : 20 : 0.5 (space : metallurgic : electromagnetic : agricultural : cryogenic : promethium), each measured in its own building type.
Oil cracking
Base-game advanced oil processing (5 second craft): 50 Water plus 100 Crude oil yields 25 Heavy oil, 45 Light oil, 55 Petroleum gas. A community balancing ratio: for every 8 refineries, run 2 heavy-to-light crackers and 7 light-to-gas crackers. Verify against a calculator for your build.
Compact patterns
- Green circuits: feed 3 copper-cable assemblers into 2 green-circuit assemblers.
- Lab and beacon: a frequently cited late-game block surrounds each lab with a ring of 12 beacons.
Watch out for
- Quoting any of these as exact for your factory. Module and research changes move them.
- Scaling the end of a chain while the front is ore-starved.
- Forgetting that productivity modules slow a machine down, so a productivity build needs more machines than the raw ratio implies.
Related: Starter Blueprints and Builds and Oil Processing and Fluids.