Free Online Date Calculators
Quick answers to everyday date questions. Pick a tool below — no sign-up, no downloads, and everything runs in your browser.
Age Calculator
How old are you, exactly? Enter a date of birth to get the age in years, months and days, plus total days, the day of the week you were born, and the next birthday.
Calculate ageDays Between Dates
Count the days between any two dates, with the answer in weeks and as a calendar breakdown of years, months and days.
Count daysDays Until — Countdown
Count down to a birthday, holiday, deadline or any future date, with a live timer showing the exact time left.
Start a countdownAdd or Subtract Days
Add days to a date or subtract days from a date. Useful for deadlines, due dates, travel dates and schedules.
Add or subtract daysDay of the Week
Find out which day of the week any date falls on — a date in the past, today, or a date in the future.
Check a dateHow these tools work
Every calculator on this site uses plain calendar arithmetic on the Gregorian calendar — the calendar used in most of the world today. Dates are handled as whole calendar days, so the results never shift with your time zone or daylight saving time. Leap years are handled automatically: February has 29 days in a leap year and 28 days in other years.
The tools run entirely in your web browser. Nothing you type is sent to a server, stored, or shared with anyone. There are no accounts and no cookies. You can read the full details in the Privacy Policy.
Which tool do I need?
- "How old am I?" — use the Age Calculator.
- "How many days are there between these two dates?" — use Days Between Dates.
- "How long until Christmas / my birthday / the deadline?" — use the Countdown.
- "What date is 90 days from now?" — use Add or Subtract Days.
- "What day of the week was 1 January 2000?" — use Day of the Week.
A note on accuracy
The calculators are built to be correct for ordinary calendar dates. The worked examples on each tool page show the method step by step, so you can check the answers by hand. If you ever spot a wrong result, please let us know through the Contact page.