its complicated. She is probably 8368 years old in LotR.
theres multiple timelines and time scales. and Tolkien contradicted himself once.
Before there was the sun, they measured time differently as well.. "Valian years", which is 9.58 solar years. (or 144 as Tolkien later stated.... which from what understand he changed to "felt like", so back to about 10)
She was born in Year of the trees 1362. which ended 1495. so 133 "valian years", which is either 1274 or 19,152 solar years..
The later ages from here, use solar years.
first age lasted 587 years,
second age 3441
the fellowship meets Galadriel in year 3019 of the third age.
so she was 5349 when the 2nd age ended, and 1908 when it started.
Now... if we use the 144 year version... Add 17,878 years to each of those...
Here is the complete timeline of Arda in J.R.R. Tolkien's Middle-earth canon - from Arda's creation to the last known events of the Fourth Age. Before the creation of the Sun, few dates can be given, and the dates that are are given in Valinorean Years, which are about a decade in length. Eru...
lotr.fandom.com
Lots of people like the 20k version as it makes Elves even more alien. but, from what I understand it messes the timeline up a bit.