Find Day of Week - Calculate What Day of Week a Date Falls On

Our free online find day of week tool calculates what day of the week any date falls on. Whether you need to know what day a specific date was or will be, this tool provides instant calculation with multiple output formats and additional date information.

How to Use the Find Day of Week Tool

Enter Date: Input date in ISO (2024-01-15), US (01/15/2024), EU (15/01/2024), or Full format
Choose Output Format: Select from Full Name, Short Name, Abbreviated, Number, or ISO Number
Include Additional Info: Optionally include extra date information like day of year, week of year, etc.
Get Result: View the day of week with additional date details

Output Formats Explained

Full Name: Monday, Tuesday, Wednesday, etc.
Short Name: Mon, Tue, Wed, etc.
Abbreviated: M, T, W, T, F, S, S
Number: 0-6 (Sunday=0, Monday=1, etc.)
ISO Number: 1-7 (Monday=1, Sunday=7)

Additional Information Provided

Full Day Name: Complete day of week name
Month: Full month name
Day of Year: Which day of the year (1-365/366)
Week of Year: Which week of the year
Is Weekend: Whether the date falls on a weekend
Is Leap Year: Whether the year is a leap year
Days Until Weekend: How many days until the next weekend
Days Until Monday: How many days until the next Monday

Use Cases for Finding Day of Week

Event Planning: Determine what day of week an event falls on
Historical Research: Find what day historical events occurred
Business Planning: Check if dates fall on weekdays or weekends
Academic Projects: Calculate day of week for assignments
Personal Use: Find out what day your birthday falls on
Programming: Get day of week for date calculations

Date Format Support

ISO Format: 2024-01-15 (YYYY-MM-DD)
US Format: 01/15/2024 (MM/DD/YYYY)
EU Format: 15/01/2024 (DD/MM/YYYY)
Full Format: January 15, 2024

Frequently Asked Questions

How does the day of week calculation work?

The tool uses JavaScript's built-in Date object to parse the input date and then uses the getDay() method to determine the day of week. This returns a number from 0 (Sunday) to 6 (Saturday), which is then converted to the requested output format.

What's the difference between Number and ISO Number formats?

Number format uses JavaScript's standard where Sunday=0, Monday=1, etc. ISO Number format follows the ISO 8601 standard where Monday=1, Tuesday=2, etc., and Sunday=7. This is commonly used in business and international applications.

Can I find the day of week for historical dates?

Yes, the tool can calculate the day of week for any valid date, including historical dates. However, note that the Gregorian calendar was adopted at different times in different countries, so very old dates may not be historically accurate.

What additional information does the tool provide?

The tool can provide day of year, week of year, whether it's a weekend, leap year status, and days until the next weekend or Monday. This information is useful for planning, scheduling, and date analysis.

How accurate is the day of week calculation?

The calculation is very accurate for dates from 1970 onwards (Unix epoch). For earlier dates, it depends on the browser's implementation, but it's generally accurate for dates back to the 1900s. Very old dates may have limitations due to calendar system changes.

Can I use this tool for programming or automation?

Yes, the tool provides both human-readable and numeric formats that are perfect for programming. The Number and ISO Number formats are commonly used in programming languages and databases for day of week calculations.