Why Travian calculators disagree

Anyone who has used more than one Travian calculator has seen them disagree. Usually neither shows its working, so there is no telling which to believe. These are the specific failure modes met while building this one.

Guessing at a value that varies

The Trade Office increases merchant capacity by a percentage per level. It was first recorded as one rate for everyone.

It is not: the Romans' Trade Office is twice as effective as anyone else's. A single shared constant silently corrupted every merchant calculation for one tribe or the other six.

The fix was not just to correct the number. The rate became a required input with no default, so nothing can compute a capacity without a verified rate. Where a tribe's base capacity could not be verified, the tool asks rather than assuming. A calculator that refuses to answer is more useful than one that answers wrongly.

Assuming bonuses add up

Do a 50% artefact and a 20% helmet give 70% off, or 0.5 × 0.8 = 40% of the original time?

They multiply - see Training time and building levels. There is a test that fails if anyone changes it to addition. This is the single highest-impact unknown in troop production, and getting it backwards inflates or deflates every result.

Applying a modifier in the wrong place

The Horse Drinking Trough reduces cavalry crop consumption. The smithy formula includes a crop consumption term. It is extremely natural to feed one into the other.

It must not: the smithy always uses base upkeep - see Smithy upgrades: what they do to your units. If the Trough fed into it, building one would retroactively weaken every cavalry upgrade owned. A test keeps these two numbers separate.

Off-by-one on an unbuilt building

Training time scales by 0.9^(level − 1). At level 0 that evaluates to 1.111 - implying a building that has not been built trains troops, slowly.

The correct answer is no production at all. Any calculator that shows troops trickling out of a Workshop that was never built has this bug.

Miscategorised data

While building the unit pages, the Viking Jarl turned up filed under "siege". It is the Viking administrator, equivalent to the Roman Senator. Because the army calculator groups Workshop units by that category, the Jarl was being offered as trainable siege - something the Workshop cannot build at all.

There is now a test asserting every tribe has exactly two expansion units, an administrator and a settler.

What this site does about it

Every figure carries a confidence level: corroborated, sheet-only, derived from other verified values, or unverified. The tools show which game version they were checked against and when.

None of that makes the numbers automatically right. It makes them checkable - and when a wrong one turns up, a transcription error can be told apart from a misunderstood rule.

Spotted one? Tell us. A report with an in-game screenshot gets the figure fixed.