About this tool
A date calculator handles the everyday "what date is it then?" questions: how many days lie between two dates, what date falls N days before or after a given day, your exact age from a birthday, and how many days remain until a future event. No counting on a calendar — just type and read the result.
It quietly handles the tricky parts like leap years and months of different lengths, and can show a gap either as a plain day count or as years, months and days. All calculation happens locally in your browser; the dates you enter are never uploaded.
How to use
- Choose a mode: days between dates / add-subtract days / age / countdown.
- In "between" mode, pick a start and end date to get the gap in days (and a years-months-days breakdown).
- In "add/subtract" mode, pick a base date and enter a number of days to get the resulting date.
- In "age / countdown" mode, enter a birthday or target date to get the age or remaining days.
When to use it
- Work out the expiry date of a contract, lease or warranty.
- See how many days remain until a due date, anniversary or project deadline.
- Get an exact age in years from a date of birth (handy for forms).
- Pin down milestones like "remind me in X days" or the end of a 90-day trial.
FAQ
Does the gap include the start day?
By default it counts the number of days between the two dates (end minus start), not counting the start day twice. If you need an inclusive count (e.g. hospital days), just add 1 to the result.
Are leap years and uneven month lengths handled?
Yes, they are handled. The tool uses the standard calendar, automatically accounting for Feb 29 and months of different lengths, so gaps that span leap years are accurate.
Is age counted as completed years?
It counts completed (actual) years — the number of full years that have passed, which matches how most official documents and forms define age. It is not a rounded-up cultural age.