Factorio quality chance explained
A normal quality module 3 adds 2.5% quality chance, so four of them in an assembling machine 3 give 10%. Of those upgrades, 90% stop at uncommon and 10% go one tier further, so only 0.01% of products jump straight to legendary.
Quality chance per module
| Module | Normal | Uncommon | Rare | Epic | Legendary |
|---|---|---|---|---|---|
| Quality module 1 | 1% | 1.3% | 1.6% | 1.9% | 2.5% |
| Quality module 2 | 2% | 2.6% | 3.2% | 3.8% | 5% |
| Quality module 3 | 2.5% | 3.2% | 4% | 4.7% | 6.2% |
The chances of all modules in a machine add up. Four legendary quality module 3 give 24.8%.
How the tier is decided
The machine rolls once against its total quality chance. On a hit, the product goes up one tier. After that, each further tier has a flat 10% chance. With four normal quality module 3 (10%) on normal ingredients:
| Result | Share of products |
|---|---|
| Normal | 90% |
| Uncommon | 9% |
| Rare | 0.9% |
| Epic | 0.09% |
| Legendary | 0.01% |
Ingredients of a higher quality start the roll from their own tier, which is why quality builds feed uncommon into a second stage, rare into a third, and so on. Recipes need ingredients of exactly the quality they make, not "at least" that quality.
Upcycling with recyclers
A recycler returns 25% of an item's ingredients and keeps their quality, and it accepts quality modules. The classic loop crafts with quality modules, keeps anything that came out at the wanted tier, and recycles the rest back into ingredients for another try. Most of the material is lost on every pass, so upcycling suits cheap items with valuable quality versions, such as quality modules themselves or items made from plentiful scrap on Fulgora.
What quality improves
- Machines craft faster: each level adds 30% of the base speed. An assembling machine 3 goes from 1.25 to 1.625, 2, 2.375 and 3.125 at legendary.
- Modules are stronger: positive module effects grow by 30% per level.
- Everything else: +30% health and spoil time per level, and beacons use less power.
- Legendary counts as a two-level jump over epic in all of these.
Quality modules do nothing in rocket silos, labs and biolabs, or in recipes that make only fluids.
Builds that use quality: quality blueprints.