How Accurate Is Argon Dating?

The age of the Earth is estimated to be 4.3 billion years old, and potassium-argon dating is accurate up to around 100,000 years before the present. Only 0.0053 percent of the potassium-40 in a rock would have decomposed into argon-40 after 100,000 years, which is close to the limit of what can be detected by our technology at this point.