Smithy upgrades: what they do to your units
Smithy upgrades are not a flat percentage. They add a term scaled by crop consumption, so two units with the same attack can gain different amounts from the same level.
Updated 13 September 2026
A common assumption is that Smithy levels add a fixed percentage to a unit's stats. They do not, and the difference shows up exactly where it matters: deciding which unit is worth upgrading.
The formula
upgraded = base + (base + 300 × cropConsumption ÷ 7) × (1.007^level − 1)
Two things are doing the work.
The 1.007^level term is the growth: each level multiplies by 1.007, compounding, so twenty levels give 1.007²⁰ ≈ 1.1497, roughly 15%.
The 300 × cropConsumption ÷ 7 term is the interesting one. It adds a slice based on how much crop the unit eats, on top of its base stat. A unit consuming 3 crop gets 300 × 3 ÷ 7 ≈ 128.6 added to the figure being scaled, whatever its attack happens to be.
Why that changes the answer
Because the crop term is independent of the base stat, a unit's percentage gain depends on the ratio between them:
| Unit | Base | Crop | At smithy 20 | Gain |
|---|---|---|---|---|
| Clubswinger (attack) | 40 | 1 | 52 | +31.0% |
| Legionnaire (cav defence) | 50 | 1 | 64 | +27.8% |
| Steppe Rider (attack) | 120 | 2 | 151 | +25.7% |
| Teutonic Knight (attack) | 150 | 3 | 192 | +27.8% |
| Haeduan (cavalry defence) | 165 | 3 | 209 | +26.6% |
The Clubswinger gains the largest percentage - its crop consumption is high relative to its modest attack. The Haeduan gains the largest absolute amount, +44 points, because it starts higher.
So: percentage gains favour cheap high-upkeep units, absolute gains favour expensive ones. Which matters depends on whether you are comparing armies of equal size or equal cost.
What the smithy does not touch
The formula always uses the unit's base crop consumption. Artefacts, the Wonder of the World village and the Horse Drinking Trough do not change the smithy calculation.
The Horse Drinking Trough is the one that catches people out. It reduces what cavalry actually eat, but it does not feed back into the smithy maths - if it did, building a Trough would quietly weaken every cavalry upgrade already bought.
Checking it yourself
Every page in the Unit database shows the smithy-adjusted values at levels 0, 5, 10, 15 and 20, and the unit comparison shows the upgraded stat with the base value alongside.