Question on upgrading units

[Hombre]

I'm currently in a game where I only have 1 other civilization which can effectively reach me and we've been at peace for a long time. Because of this, I haven't been extremely focused on building units, (I'm trying to culture bomb instead), and a lot of my units are obsolete. I have built city walls in my border cities and have a few modern units in each one so I don't feel there's any immediate rush to increase my military. I have plenty of gold to do a lot of upgrading if I decide to, but I'm not sure if it would cost me more money to upgrade now, and then upgrade again when I get a few more techs, or if it's cheaper to wait and then upgrade only once. Is there a simple formula for figuring this out?

[Quillan]

I'm not sure I'm remembering this correctly, but I think it was a base of 25 gold plus 3 or 4 per hammer difference between the production costs of the original and upgraded unit. So yes, it will cost you an additional 25 gold per unit if you upgrade it twice.

[vmxa1]

The thing I care about is will I need the unit active next turn? So I would rather spend the gold that I can afford now and not get caught with my pants down.

I have had many ocassions where all I could do was upfrade and not press the unit into action. This usually mean loss of tile and it will be gone for a long time as I will probably not be able to risk a worker very soon.

[Dis]

the question I wonder about is if the AI noticed the difference in power when you upgrade. I think they do. I think they would be less likely to attack if they sense you have a stronger army. Unless you want them to attack...

[Cort Haus]

Originally posted by Dis
the question I wonder about is if the AI noticed the difference in power when you upgrade. I think they do. I think they would be less likely to attack if they sense you have a stronger army. Unless you want them to attack...

Yes, I think the AI keeps its eye firmly on the F9 screen at the military numbers, and uses that to decide who to issue threats / demands / attacks on. Also the 25g surcharge for upgrading does mean that skipping an upgrade does save money, but being militarily weak usually ends in trouble.