Does anyone know if there's a mod somewhere that says how many days old a Sim is instead of how many days left to the next age? Like in the elder state when it says they're x days old. I'd like that to be the default for every other age so it's easier to calculate their age in years. It's just tedious trying to math it all out in reverse.

There is a mod that says how many days left a sim has in the current life state, if that would help? It's by Simlogical, days left shrub.

link to the aforementioned:
https://simlogical.com/sl/Sims2Pages/Sims2_Aging.htm

Excellent! Thank you both very much. I could have sworn there was something like this but couldn't for the life of me remember what it was called.

If you have ACR installed, it can list the number of days. Unfortunately only teen and older.

Good to know, thanks. I've never played with ACR but I'm planning on adding it to my test hood to see whether I like it.

The days left shrub just does the opposite of what OP wants though, doesn't it? Because you can already see how many days left a sim has except if they are elders.

I also use the ACR dialog to show number of days old, and haven't found a better way to do this. For toddlers/kids/teens I just have a notepad file with a conversion table.

I did think about writing a mod which uses this to get the game to pop up with a notification saying "The sim is now 60 days (30 years) old" but I don't really need it for myself and I can't be sure other people are playing with the same age duration as me so it probably wouldn't be that useful to others either.

Good catch. I must have read the description of the shrub wrong, I haven't tried installing it into my game yet.

I was using a conversion table too, I was just hoping there was an easier way. At least ACR makes it a little easier. Thanks for your input.