Age Calculator
Exact age, days between dates, business days, date math and countdowns — one free calculator, nothing uploaded.
Free · No sign-upHow to use the age & date calculator
- 1. Pick a tab: Age, Days between, Add / subtract or Countdown.
- 2. Enter the dates. Results update instantly — for age, leave “Age on” empty to use today.
- 3. For deadlines, tick Include the end day if both days count, and keep Skip US federal holidays on to get true business days.
- 4. Tap Copy result for a one-line summary, or Copy share link to send the exact calculation to someone.
Frequently asked questions
How is exact age calculated?
We count whole years, then whole months, then the leftover days, the same way people and most legal forms do. When a month is shorter, the date is clamped to its last day, so January 31 plus one month is February 28 (or 29).
When does someone born on February 29 have a birthday?
In leap years, on February 29. In common years the calculator uses February 28, the convention followed by most US states for legal age; some countries use March 1 instead.
How do I count business days between two dates?
Open Days between, enter both dates and read the business days figure. It skips Saturdays, Sundays and the 11 US federal holidays on their observed dates (a Saturday holiday moves to Friday, a Sunday holiday to Monday). State and company holidays are not included.
Should I include the end date?
Leave it off for deadlines, loan terms and “days until” questions — January 1 to January 2 is one day. Turn it on when both days count, such as a hotel stay, a vacation or a leave request, which adds one day.
Can the end date be earlier than the start date?
Yes. Enter the dates in any order; the result is labeled as counting backwards, which is handy for “how many days ago was…” questions.
Is my data private?
Yes. All calculations run in your browser and nothing is sent to a server. A share link stores the dates after the # in the URL, which browsers do not send to websites.