Konoha was founded during the warring clan era by Hashirama and Madara. Now, to have the power and get acknowledged by the other clans to create konohaKonoha, they have to have been somewhere between age 25 to 35. Hashirama's brother, the 2nd hokageHokage, would have been around the same age too.
In a flash backflashback, we can see that the 2nd hokageHokage was just around 30 years old when he was killed by the goldGold and silverSilver brothers.
And the 3rd hokageHokage has been his disciple since being a genin. From this, we can say that konohaKonoha was created just around the same time as when the 3rd hokage was born.
And he was 68, iI think, when he was killed by the snakeSnake sennin. Add another 30 years and when borutoBoruto takes place.
So add some 5 years for the 1st hokages term. Add another 5 years for 2nd hokages term. Add around 55years for 3rd hokages term. And another 5 years for 4th hokages term. (Start of cannon) Add 13 years till naruto is gennin Then add three 3 years for the time skip (Naruto Shippuden) Then add 30 years for skip to when boruto takes place.In short:
- Add some 5 years for the 1st Hokage's term.
- Add another 5 years for 2nd Hokage's term.
- Add around 55 years for 3rd Hokage's term.
- And another 5 years for 4th Hokage's term.
- (Start of canon) add 13 years till Naruto is gennin
- Then add 3 years for the time skip
- (Naruto Shippuden starts) Then add 30 years for the skip to when Boruto takes place.
So totally konohaKonoha is around 110 years old.