日期计算器

The Date Calculator answers two questions people run into constantly: how much time sits between two dates, and what date lands a certain number of days, weeks, or months from today. Instead of counting boxes on a calendar or doing manual math with leap years, you get an instant, accurate answer. It's built for things like figuring out someone's exact age in years, months, and days, counting down to a deadline or event, checking how many days are left on a lease or warranty, or working out how many business days a project has consumed.

The tool covers two distinct calculations. In difference mode, you enter a start date and an end date and it returns the total span between them. In add/subtract mode, you start from a single date and add or subtract a number of days, weeks, or months to find a resulting date — useful for scheduling a follow-up, calculating a due date, or backdating a deadline. Both calculations happen the moment you change an input, so you can adjust dates and immediately see how the result shifts.

Because every calculation runs client-side in your browser, nothing you enter is uploaded or logged anywhere — handy if you're calculating something personal like an age or a legal deadline. There's no account, no waiting on a server round-trip, and the tool works the same whether you're checking a single date or running the numbers repeatedly while planning a schedule.