🧮 Calculators & Daily Life

Date Calculator

Find the gap between two dates, land on a date N days/weeks/months/years out, or check exact age and days since birth. Handy for deadline tracking, anniversary countdowns, and contract period checks. Nothing leaves your browser.

Examples (click to try)

How to Use the Date Calculator

Use the tabs at the top to switch between three calculation modes. Results are displayed automatically as soon as you enter dates.

Date Difference

Select a Start Date and an End Date to see the number of days, weeks, approximate months, and approximate years between them. Useful for confirming project durations or calculating contract periods. If the end date is earlier than the start date, the result is shown as a negative number.

Example: enter Start Date "2024-04-01" and End Date "2025-03-31" and the difference shows as 364 days (52 weeks, about 12 months, about 1 year). Clicking "Difference between two dates" under "Examples (click to try)" fills in exactly these values.

Add / Subtract

Enter a Base Date, a number, and a unit (Days / Weeks / Months / Years) to find the date that many units before or after. Use the After / Before buttons to switch direction. When adding months or years would result in a day that does not exist in the target month (e.g., one month after January 31 = February 31), the date is automatically adjusted to the last day of that month.

Age Calculator

Enter a date of birth and a reference date to see the exact age, total days since birth, and days until the next birthday. The reference date defaults to today, but you can change it to any date to check the age as of a specific past or future point.

Handy use cases

  • Check how many days remain until a project deadline
  • Find the exact date of a contract renewal or payment due N months out
  • Verify age for a resume, job application, or celebration
  • Count down to an anniversary or birthday

Frequently Asked Questions

Is my input data sent to a server?
No. All date calculations happen entirely in your browser. Your input is never transmitted to or stored on any server, so you can use this tool with confidence.
How does month-end overflow work when adding months?
If the result falls on a day that does not exist in the target month — for example, one month after January 31 would be February 31 — the date is automatically adjusted to the last day of that month (February 28 or 29 in this example).
How do I change the reference date for age calculation?
In the Age Calculator mode, a Reference Date field is shown. It defaults to today's date, but you can change it to any date to check the age as of a specific past or future date.