25 years old; my grandmother died in 2013.
39 YO; my maternal grandmother died in 1999 at the age of 90.
I never knew either of my grandfathers. My paternal grandmother died in 1962, when I was 13. My maternal grandmother died in 1966, when I was 17.
Ten. My father’s parnts both died before I was born. My mothers parents died I think when I was about 8 and 10. My grandmother never spoke English. I probably already answered this, I’ve made some posts here I can’t remember.
Forty for me. My mom’s mom died at 93 just before I turned 41.
I was 14 when my great-grandmother (My dad’s mom’s mom) died.
40, since it was early last year.
I’d just turned 40.
My wife’s 53 and one of her grandparents is still alive, although at this point it’s more a case of the body lingering on after the mind has gone.
Just to mention, in addition to the above I lost the last blood relative from my parent’s generation at age 59. My deceased father’s last living sibling. (My mother was an only child.) I still have a couple of aunts by marriage but am now at the top of the heap geneticswise.
I wonder who in this thread was the oldest when their last grandparent died.
I must be up there as I was 57, and my maternal grandmother just short of 108 when she died.
That doesn’t look very clear. I was 59, my uncle was 97.
I’m 51, born in 1967.
The great-grandparents:
Gramma J, 1978
Gramma McD, 1970
Gramma K, 2003
Gramp K, 2000
Gramp E, 1977
The grandparents:
Gramma J, 2000
Gramp J, 2008
Gramp D, 1998
Gramma D, 2018
When I was born, I had four living grandparents and two greats (my maternal grandmother’s parents). One great died when I was one and the other when I was 6. When I was 17 my maternal grandfather died and the other one when I was just a month short of 19. My maternal grandmother died when I was 25 and the other one about a year later.
My paternal grandmother at 16. On my birthday! My Dad woke me up and told me.
My paternal grandfather at ~18
My maternal grandmother -early 20’s
My maternal grandfather -mid 30’s
My maternal grandmother went like Elvis. On the bowl! My Aunt who found her said she looked so peaceful sitting there!
I apparently missed this thread in its original incarnation, and both revivals. 
I was 29 when my final grandparent (my maternal grandmother) died, in 1994.
The other three:
- Paternal grandfather died when I was 5.
- Maternal grandfather died when I was 18.
- Paternal grandmother died when I was 26.
Neither of my parents were terribly old when I was born (dad was 31, mom was 24), but all of my great-grandparents were already gone by that point.
I was 19 when I lost my last grandparent - paternal grandmother. I lost her, my best friend at the time in college (single car drunk driving accident) and my horse (cancer) all in the course of a few days…that was a tough week…
47 - it just happened three months ago, my maternal grandfather, bless his memory.
Maternal Grandfather: 11
Paternal Grandather: 22
Maternal Grandmother*: 26
Paternal Grandmother: 29
*Her mother died when I was 13.
Only really knew one alive; maternal grandmother who lived with us when I was growing up. She died when I was roughly 36. Decorated her grave today which is one of the reasons I decided to post; a lot of memories are fresh in my brain of those 36 years.
I was 44 when my last grandparent died, 8 when the last great grandparent died.
One died (days) before I was born. The others went when I was 17, then 35, and then finally 36.