How far out will the sun reach when it turns into a red giant?

When the Sun becomes a red giant, it is expected to expand significantly, potentially reaching out to the orbit of Earth, which is about 1 AU (astronomical unit) or approximately 93 million miles (150 million kilometers) from the Sun. Some estimates suggest it could extend even further, possibly engulfing the inner planets, including Mercury and Venus. This transformation will occur in about 5 billion years as the Sun exhausts its hydrogen fuel and begins to burn helium.