The base revolt power starts at 1 and then two factors are added. The first is 2x the city's highest ever population. The second is the number of directly adjacent squares that the revolting people's civilization controls times the current game era. Current game era is considered to be the average era of the remaining players, rounded down, with ancient being considered '1', medieval '2', and so on. So, in the final era (6), if the side the city wants to revolt for controls all 8 squares around the city, this could be as high as 48.
The base revolt power is then multiplied by several factors. The first is the ratio of the two sides' plot culture for the city square. The formula for this multiplier is 1 + ((revoltCulture - cityOwnerCulture) / (revoltCulture)). This would be a number between 1 and 2, being near 2 if the revolt's plot culture is much higher than the owner, and being near 1 if the two are almost equal. If the revolt's plot culture is twice that of the city owner (i.e., 67% revolting nationality, 33% owner nationality), the value would be about 1.5. Sorry for the ugly math, but I can't find a way to explain it more simply at the moment.
Fortunatly, the other multipliers are a bit simpler. If the revolting civilization's state religion is present, the value is doubled. If the city owner's state religion is present, the value is halved. If both are present, these two multipliers cancel each other out. If somebody doesn't have a state religion, they don't get a multiplier.
The city's garrison strength is also simple. Start at 1 and add the cultural garrison strength of all units in the city, regardless of ownership. Double this if the owner and revolting civilization are at war. The only catch is that cultural garrison strength can't be found in game, so here is a list of unit values:
The city's garrison strength is also simple. Start at 1 and add the cultural garrison strength of all units in the city, regardless of ownership. Double this if the owner and revolting civilization are at war. The only catch is that cultural garrison strength can't be found in game, so here is a list of unit values:
warrior, quecha: 3
archer, skirmisher, axe, spear, phalanx, chariot, immortal, catapult: 4
swordsman, jaguar, praetorian, horsearcher, keshik, war elephant: 5
mace, samurai, pike, longbow, crossbow, chokonu, knight, camelarcher, conquistador: 6
musketman, musketeer, grenadier, cannon: 7
rifle, redcoat, calvalry, cossack: 8
machine gun: 9
infantry, SAM infantry, gunship, artillery: 10
marine, SEAL, tank, panzer: 12
mech infantry, modern armor: 16
Note that ships, planes, workers, great people, and other non-military or non-land units don't help keep a city under control.
[/b]