Age Calculator — Exact Age & Days Between Dates
Enter a date of birth to get your exact age in years, months, and days, how many days you’ve been alive, and how long until your next birthday. The second tool measures the gap between any two dates in days, weeks, and a calendar-accurate years-months-days breakdown — useful for forms, anniversaries, projects, and deadlines.
How age is counted
Age is the completed years, months, and days from your birth date to today — the same convention forms and officials use. Months differ in length, so the calculator borrows the correct number of days from the previous month rather than assuming 30.
Days between two dates
The date-difference tool counts whole days from the earlier date to the later one, then expresses the same span in weeks and in years-months-days. Swap the dates and the answer is the same magnitude — order doesn’t change the gap.
Where it’s handy
Visa and pension age checks, working out a baby’s age in months, counting down to an event, tracking how long since a milestone, or measuring a project’s run length in days for billing.
Common mistakes
Counting both endpoints (off-by-one); assuming every month is 30 days; and ignoring leap years — the calculator handles all three using real calendar dates.
Frequently asked questions
- Does it count leap years correctly?
- Yes. The calculation uses actual calendar dates rather than a fixed 365-day year or 30-day month, so leap days and varying month lengths are included automatically.
- Why might my age in days surprise me?
- Days add up fast: 30 years is over 10,950 days. The day count also includes leap days, so it won’t equal years × 365 exactly.
- Does the date difference include both endpoints?
- No — it counts the whole days from the start date to the end date, not both ends. If you need an inclusive count (for billing every day in a range), add one.
How we calculate it
Age is the completed years, months, and days from the birth date to today, borrowing the previous month’s real length when the day-of-month goes negative. Date difference counts whole days between the two dates (smaller to larger) and also expresses it in weeks and in years-months-days. Real calendar dates are used, so leap years are handled.
What it doesn't do
- Time-of-day or timezone precision (whole days only)
- Business-day counts that skip weekends and holidays
- Historical calendars before standard Gregorian dates
Last reviewed: 2026-05