According to new legal docs ... just a "portion" of the rapper's estate is worth more than $4.48 million. This amount is the sum of various checking, savings and money market accounts ... as well as 200 shares of Facebook stock worth more than $32k.

The docs point out Miller didn't own any property in California at the time of his death, but it's unclear if he owned real estate elsewhere. The $4.48 mil also doesn't include other potential property like cars, artwork or collectibles ... so it's possible he's worth a lot more.

We broke the story ... Miller died at his home in San Fernando Valley in September. The cause of his death was ruled an accidental overdose from a mix of fentanyl and cocaine.

As you know, Mac's been nominated for a Grammy posthumously, so if he wins Sunday night ... a Grammy Award can be added to his net worth.