Tested
Day of the Week Calculator
Find the weekday of any date.
Date & Calendar Tools
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Free date & calendar tools for everyday questions, from quick checks to detailed breakdowns.
Date & Calendar tools (5)
- Tested
Day of the Year Calculator
Which day of the year a date falls on.
Date & Calendar Tools
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Leap Year Calculator
Check whether a year is a leap year.
Date & Calendar Tools
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Week Number Calculator
ISO week number for a date.
Date & Calendar Tools
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Weekday Calculator
Look up the weekday (Monday to Sunday) of any past or future date.
Date & Calendar Tools
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All date & calendar tools by topic (49)
Age
Birthdays
Calendars
Date Math
Holidays
- Days Until Christmas
- Days Until Christmas Eve
- Days Until December
- Days Until Easter
- Days Until Father's Day
- Days Until Halloween
- Days Until Inauguration Day
- Days Until International Women's Day
- Days Until Juneteenth
- Days Until Labor Day
- Days Until Leap Day
- Days Until Memorial Day
- Days Until MLK Day
- Days Until Mother's Day
- Days Until New Year's
- Days Until New Year's Eve
- Days Until Presidents' Day
- Days Until St. Patrick's Day
- Days Until Thanksgiving
- Days Until the Fourth of July
- Days Until Valentine's Day
- Days Until Veterans Day
- New Year's Countdown
- Weeks Until Christmas
- Weeks Until Easter
- Weeks Until Halloween
- Weeks Until Thanksgiving
About date & calendar tools
Date & Calendar Tools help you turn a question into a clear, checkable answer. Each tool lists its inputs, shows the formula it relies on and explains how to read the result.
Browse by topic using the filters, or search for a specific tool. Tools that are still being built are clearly marked as previews and are not presented as finished calculators.
Frequently asked questions
Are the date & calendar tools calculators free?
Yes. Every calculator on Calculator Atlas is free to use and requires no sign-up.
How are results verified?
A calculator is only published after its formula has been implemented, tested against reference values and reviewed. Pages still in development are labeled as previews.