Exact age counts the years, months, and remaining days from your birth date to today. A full year is counted only after the same calendar date passes in a later year. This is the internationally standard way of expressing age (used in legal and medical contexts worldwide).
At exactly 10,000 days old (roughly age 27), at 1 billion seconds (about age 31.7), or at 100 million minutes (about age 190) — these are popular personal milestones worth calculating. Enter a future date in the "as of" field to see how old you'll be at any given time.