Question about aging

How do you handle aging in your game? I know you have years and ages for the sims, but how long is each year, and how many years are each age group?

I found one post from several years ago that said that each year is 20 days long, but you may have changed it since then.

each year is 20 sims days (4 season's each 5 days long) as for years in each age group it really depends on the sim and what i need to do with them for photo's etc. but the general "theory" is something like

Baby - till 20days old (1 year)

Toddler - till 4 years

Child - till 12 years (sometimes abit earlier, for example maegan was 11 because i needed her not to look stupid with chris in her first appearances as his betrothed/wife and having her in the child lifestage would have been kinda creep and wrong)

Teen (Boys till 15, Girls Skip unless going to uni)

Independent Teen till 18.

Adult Till (Varies .. again depending on the charecter and what storylines im doing and how it will look for them to suddenly age, so i tend to start graying hair in adult stage and then wait for a story not to involve them for a while before aging, usually around 50)