Date Calculator

Choose a mode to add or subtract time from a date, or compute the difference between dates with totals.

What can this Date Calculator do?

• Add years, months, and days to a starting date
• Subtract years, months, and days from a starting date
• Calculate the exact difference between two dates, with totals for days, weeks, hours, and minutes

Best practices

• Calendar math is nuanced: months have varying lengths and leap years exist. This tool uses calendar‑aware add/subtract and approximations for month/day breakdowns in differences.
• For compliance or legal contexts, confirm results against your jurisdiction’s definition of business days/holidays.
• Use ISO format (YYYY‑MM‑DD) to avoid locale ambiguity.
• When communicating results, include both a formatted date and the ISO string for clarity.

How to use

1. Pick a mode: Add Time, Subtract Time, or Find Difference.
2. Enter a date (and an end date for difference).
3. Provide years, months, days when adding or subtracting.
4. Click Calculate to see the result or totals.

Examples

• Add 1 year, 2 months, 10 days to 2024‑01‑15 → shows the target date and a friendly format.
• Difference between 2020‑06‑01 and 2025‑09‑01 → years, months, days plus total days/weeks/hours/minutes.

FAQ

Does it handle leap years?
Yes—date arithmetic uses JavaScript’s calendar rules, so Feb 29 handling follows actual year rules.

Why do months/days in the difference sometimes look approximate?
Month/day breakdown uses average month length for readability; totals (days, weeks, hours, minutes) are precise.

Can I calculate working days only?
This version returns calendar days. For business‑day calculations, use totals and apply your organization’s holiday list.

Which format should I use?
Use YYYY‑MM‑DD for unambiguous input and copy the formatted output for readability.

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