So I just refreshed my TU on Credit Karma, my score overall jumped 63 points to 721, and my AAoA dropped to NEGATIVE 2209 days, or 0y5mo. Must have been my Barclay card I activated
@Anonymous wrote:So I know that a high average age of accounts is a positive thing for your credit score, and report. My question is, is how is it calculated?
Reviewing my score on Credit Karma, shows that I have an AAoA of 6 1/2 years. I have a total of 6 open tradelines, but only have had a credit card since January of 2011.
AAoA takes in account all TL's on your profile. Do you have any installment loans?
@bichonmom wrote:Total months you've had each card/account multiplied by the number of accounts/cards = Total months of all of your accounts. Divide that number by total number of accounts = AAoA
@Anonymous include any closed accounts as long as they are still reporting on your CR. The # of months would start @ opening date through current month. If it's closed and not reporting, then it doesn't get calculated in AAoA at all.
This part confuses me. Why would you multiply by the number of accounts and then turn around and divide by the number of accounts? This is how I calculate AAoA:
Your AAoA is the sum of the ages of every account (except CA collections and public records) on your report, whether open or closed, calculated in months, divided by the number of accounts and then divided by 12. I use the division by 12 to make it easier to convert into years. This is measured from the time each account was opened until present.
You can never have an AAoA of less than one year. This is built into the system.
You’ll need to figure the age of each account, open or closed, on each report. If all three reports are identical (very unlikely), you're in luck; otherwise, you'll need to run this for each report.
Disclaimer: Math was never my best subject and we could very well be arriving at the same destination using different routes. 
