Online Date Calculator
Date difference and add/subtract days, with automatic leap year and weekday handling, fully client-side
FAQ
Pick a start and end date and the tool computes the absolute difference in days, then converts it to full weeks, remaining days, and approximate years (365.25 days) and months (30.4375 days).
Yes. Enter a negative number (e.g. -30) in Add/Subtract mode to get a date 30 days earlier. Cross-month and cross-year math is handled automatically.
Yes. Feb 29 is valid in leap years like 2024 and rejected in non-leap years like 2023.
No. All calculations happen locally in your browser. Your data never leaves your device.
Month and year lengths vary, so the tool uses average lengths (365.25 days/year, 30.4375 days/month). Use the day count for exact results.
Completely free. This is a pure frontend online tool - no registration required, no payment needed, just open and use.
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