Date Calculator
Pick a start date, enter an amount of time, and choose whether to add or subtract. The result date appears instantly — great for deadlines, lead times, notice periods, and project planning.
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Frequently Asked Questions
What is a date calculator used for?
A date calculator lets you add or subtract a span of time — days, weeks, months, or years — from a specific date. Common uses include finding project deadlines, delivery dates, notice periods, subscription renewals, and contract expirations.
What is the difference between adding days and adding months?
Adding days is always exact: 30 days is always 30 days. Adding months jumps by calendar month, which can vary from 28–31 days. For example, adding 1 month to January 15 gives February 15, but adding 1 month to January 31 gives March 3 (since February has no 31st).
Can I use this to calculate a date in the past?
Yes — switch to Subtract mode to go backward in time. For example, you can find what date was 90 days before today, or before any specific date you enter.
Does this handle leap years?
Yes. When adding or subtracting days or weeks, leap years are handled naturally because the calculation counts actual calendar days. When adding years, February 29 is preserved if the target year is also a leap year; otherwise it is clamped to February 28.
Is my data saved or sent anywhere?
No. All calculations happen in your browser. Nothing is sent to a server and nothing is stored between sessions.