CountdownStopwatch

Date Tools

Date Calculator

Add or subtract days, weeks, months, and years with clear month-end behavior.

Choose values, then calculate.

Date-only calculations avoid timezone drift where practical. Business-day results do not include public holidays unless you explicitly add excluded dates in a future version.

How to use Date Calculator

Set the values you need, press Start, and keep this browser tab open. Most tools store only practical preferences locally in your browser.

Timer accuracy is based on timestamps, so the display corrects itself after tab backgrounding. Browser alarms and notifications still depend on browser permission, power state, and open-tab behavior.