The Civilinic Books

Trade Route Formula
by Elephant

This new thread pulls together data on Civ2 Trade Route formulas from several previous posters and threads, most importantly the How to Maximize Trade Between Two Cities:
How To Maximize Trade Between Two Cities? The Basic Formula comes from the Civ2 Manual; the Multipliers and their order are based on Samson's
Calculating Caravan and Freight Delivery Payments

This thread attempts to formalize the "ongoing" Trade Routes, not the one-time Caravan/Freight Delivery Bonus.

All multiplication and division are Civ2 integer math: remainders are dropped.

T1 and T2 are "Total Base Trade Arrows" of Source and Dest cities

Base Trade Modifiers
-1in Despotism for each tile that has >2 trade arrows
+1for each land tile with River
+1for each road on Grass/Plains/Desert tile
+1for each road on tiles with >0 arrows ("special" tiles or rivered)
+1in Rep, Dem, or Celeb-King/-Commy/-Fundy for each tile >0 arrows
+1for Colossus for each tile >0 arrows
x1.5with SuperHighways for each land tile >0 arrows with road/railroad
x??? Base Trade Corruption Loss
(apply in order listed, discarding remainders)
NO Map Size multiplier
1). (x???) Secondary Corruption Loss (first or last?)
NO Different Continent multiplier
2). (x0.5) Same Civ multiplier
NO FreightVsCaravan multiplier
NO Demand multiplier, just Dem/Sup blocking effects
3). Transportation multiplier(add together before multiplying?)
+50% for KeyRoad Source->(alt: StationCity; limit: 22), OR<7td>
+100% for KeyRR Source->>Dest
+50% for SuperHighways in Source city (increases BaseTrade too)
(NO+100% for SH in both cities, just Dest Base Trade increase)
+50% for Airports in both cities, same or diff continent
NOTE: Airports Factor superceded by RD/RR Factor!
NO AgeModifier
Rules of Thumb
BESTSame Continent KeyRR with SH to AI city+150%
NEXTDiff Continent SH, AP to AI city with AP+100%
SAMESame Continent KeyRD with SH to AI city+100%
OWNSame Continent KeyRR with SH+075%


Once a city has 3 Trade Routes a new delivery may replace one of the existing routes. If a route already exists to the Destination city, the commodity listed will be changed to the newer commodity. If a route to the Destination city does not exist, the computer compares the Base Trade values of all existing plus new Destination cities and keeps the routes to the cities with the three highest values. Multipliers are ignored in comparing Trade Routes for replacement. To keep from replacing an existing Trade Route with higher multipliers (such as replacing a TR to AI city with one to domestic city), lower the Base Trade value of the new city below the values of existing cities (of course, this will lower the Bonus Payment amount some, but if the Destination city is the SSC/STC with over 100 trade arrows the difference may be small). Rule of Thumb for trade arrows in AI cities is 1 per citizen in Desp/Mon/Commy/Fundy, 1.5 in Rep/Dem.

HELP! - I need help checking these formulas. First of all, I cannot find any Corruption Loss formulas that differentiate between Base Trade and Trade Routes. SlowThinker's thread on Corruption lumps it all together, but my testing indicates there are two factors involved. Secondly, I don't have enough testing to prove the order of multipliers and the additive nature of the Transportation multiplier - I just took that from Samson's thread. I need players to apply these formulas as specified in their own games and post here any anomalies.
Please post save games with a description of the deviation issue being challenged. "I'm pretty sure..." will not be accepted.

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