It is worthy to note that nobody can determine the exact age of Earth because the oldest rocks in Earth have already been destroyed through the process of plate tectonics. However, if we are going to take into consideration the oldest Earth rocks that were found and available when the research was made, it is arguably correct to say that Earth’s age is approximately 4.55 billion years – this age is based on the pieces of evidence from radiometric age-dating of meteorites (a technique used to date materials to know when they were formed). The oldest rocks on Earth are the Acasta Gneisses which can be found in the northwestern part of Canada with 4.03 Ga (one billion years). Hope this helps!