Age & DatesDATE & AGE TOOL
Date Calculator
Add or subtract days, weeks, months or years from a date.
How this calculator works
This tool uses calendar dates directly. Date differences are calculated from UTC-normalized calendar dates to avoid daylight-saving-time changes affecting the result. Calendar age counts complete months from the starting date, then remaining days. When a month is shorter, the date is clamped to its last day. For this tool, a 29 February birthday is observed on 28 February in a non-leap year. These are calculation conventions, not legal eligibility rules.
Why use this tool?
It is designed for quick, transparent calculations without requiring an account. Your date inputs are processed in your browser by the current version of the site.
Frequently asked questions
Does this calculator account for leap years?
Yes. Calendar calculations use the actual dates in the Gregorian calendar, including leap years.
Do you store my date of birth?
The calculator processes dates locally in your browser. We do not send the entered dates as analytics events. See our privacy information for site analytics details.
Keep exploring
How do I add or subtract time from a date?
Choose a starting date, a whole-number amount, a unit and whether to add or subtract. Days and weeks count calendar days, including weekends. Months and years preserve the day number where possible and otherwise use the final day of the target month.
Worked example
31 January 2025 plus 1 month is 28 February 2025. This tool does not exclude weekends or public holidays.