The Sun is estimated to be about 10 - 20 million years older than Earth, and by radioactive dating, Earth is about 4.5 billion years old, so that the Sun is therefore a tad younger than this around 4.51 billion years. Note, some of the oldest meteorites are 4.8 - 4.9 billion years, but the trapped dust grains can be much older than the Sun because dust grains formed in old stars 10's to 100's of millions of years before they got to the cloud out of which the Sun and planets formed.
