Researchers calculate the age of the Earth by dating both the oldest rocks on the planet and meteorites that have been discovered on Earth (meteorites and Earth formed at the same time, when the solar system was forming). Their findings? Earth is about 4.54 billion years old.
(Photo shown here, what may be the oldest known rocks on Earth, called the Nuvvuagittuq Belt on the coast of the Hudson Bay in Northern Quebec, and dating back to 4.28 billion years ago, scientists estimate.)
One has only to look at the walls of the Grand Canyon to confirm how old the Earth is.
https://en.wikipedia.org/wiki/Grand_Canyon
The Grand Canyon is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is 277 miles long, up to 18 miles wide and attains a depth of over a mile (6,093 feet).
Nearly two billion years of Earth's geological history have been exposed as the Colorado River and its tributaries cut their channels through layer after layer of rock while the Colorado Plateau was uplifted. While some aspects about the history of incision of the canyon are debated by geologists, several recent studies support the hypothesis that the Colorado River established its course through the area about 5 to 6 million years ago.