Date Add/Subtract Calculator

Add or subtract days, weeks, months, or years from any date

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Common Use Cases

Deadline Planning

Add days or weeks to find project due dates

Subscription Tracking

Calculate when monthly or yearly subscriptions renew

Event Scheduling

Find dates for events happening weeks or months from now

Age Calculations

Subtract years to find birth dates or past anniversaries

Interesting Facts & World Records

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Missing Days in History

In 1752, Britain skipped 11 days (Sept 3-13) when switching from Julian to Gregorian calendar

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Oldest Known Calendar

The oldest known calendar is about 10,000 years old, found in Scotland, tracking lunar phases

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Lunar vs Solar

The Islamic calendar is lunar-based, making it about 11 days shorter than the solar Gregorian calendar

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Leap Year Rule

Years divisible by 100 are NOT leap years, unless also divisible by 400 (2000 was, 1900 wasn't)

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February 30th Existed

Sweden had a February 30th in 1712 while transitioning calendars - the only time it ever existed

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Ethiopian Calendar

Ethiopia is about 7 years behind the Gregorian calendar and has 13 months in a year

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10,000 Year Clock

Jeff Bezos is building a clock designed to run for 10,000 years inside a Texas mountain

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World Calendar Proposal

The World Calendar proposed in 1930 would have made each quarter exactly 91 days, but was never adopted