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Date Calculator
Compare two dates, or start from one date and add a span. Month-end and leap rules are stated on the page.
Difference between two dates
Add to a date
Invalid dates such as 31 February are rejected by the date picker and by the strict check behind this tool — they are never silently rolled over to March.
Questions
What happens with month-end dates?
Adding months clamps to the last day of the target month: 31 January plus one month is 28 February, or 29 in a leap year.
Are impossible dates accepted?
No. Dates such as 31 February are rejected instead of being silently rolled over to March.