Date and Calendar Tools

Counting days

• Add Days to Date

  Add calendar days to a date with option to include the start date.

• Days Between Dates Calculator

  Calculate the number of days between two dates with options to include or exclude the start and end dates.

• How Many Days Until a Date

  Days Calculator: from today to any future date.

• Subtract Days from Date

  Subtract calendar days from a date with the option to include or exclude the start date.

• Convert Days to Weeks

  Days to weeks converter with remaining days.

• Convert Days to Months

  Days to months converter with customisable month length. Calculates full months and remaining days.

Counting working days

• Add Working Days to a Date

  This calculator adds working days to a date, skipping weekends and bank holidays. It shows the completion and handover dates.

• Working Days Calculator Between Dates

  Shows the number of working days between two dates, accounting for weekends and bank holidays.

• Subtract Working Days from a Date

  The calculator subtracts working days from a date, skipping weekends and bank holidays.

Counting weeks

• Weeks Between Dates Calculator

  Calculate full weeks and remaining days between two dates.

• Add Weeks to Date

  Add full weeks to any date and find out the resulting date with the day of the week.

• Subtract Weeks from Date

  Subtract a specified number of full weeks from any date.

• Convert Weeks to Days

  Weeks to days converter, accepts whole and fractional week values.

Calendar

• Calendar for Any Year

  Calendar with year navigation and week start selection.

• Shift Calendar

  This tool is designed for visualising work schedules. It generates a calendar grid based on a specified shift cycle and start date.

• Working Days and Days Off Calendar

  Display of the schedule for the selected year with dates categorised as working days, weekends, and public holidays.

• Day of the Year by Date

  This tool determines the ordinal day number in the year for any selected date. Enter the day, month, and year to calculate the number from 1 to 366.

• Date by Day Number in Year

  This tool converts an ordinal day number to a calendar date (day, month, and day of the week) based on the number and specified year.

• Week Number in Year by Date

  Shows the week number for any date using ISO 8601 (international) or US (traditional, from 1 January) standards.

• Full Weeks in a Year Calculator

  Calculates how many full weeks fit in a specified year with a choice of first day of the week.

Age

• Age Calculator

  Calculate age by date of birth for today or any other date.

• Age Difference Calculator

  Tool for calculating age difference by birth dates. Results in years, months and days, plus the absolute number of days between birth dates.

• Find Your Birth Day of the Week

  The tool will show the day of the week for the specified date of birth.

Counting time and dates

• Add Time to Date and Time

  Add any number of hours and minutes to a starting date and time.

• Subtract Time from Date and Time

  Subtract time in hours and minutes from a starting date and time.

• Time Between Dates Calculator

  Calculate time difference: from minutes to days between two dates.

Counting months

• Add Months to Date

  Adds a specified number of months to a date with a choice of calculation method: calendar or mathematical.

• Subtract Months from Date

  Subtracts a specified number of months from a date with a choice of calculation method: calendar or mathematical.

• Months Between Dates Calculator

  Calculate calendar months and remaining days between dates.

• Convert months to days

  Months to days converter with customisable month length.

Counting years

• Years Calculator Between Dates

  Shows how many years between two dates and the remainder in months and days according to the calendar.

• How many years have passed since a year

  Calculate the number of years from a specified year to today, with support for BCE dates.

Useful materials

• Date Calculator Structure and Calculation Methods

  An exploration of date calculators: how algorithms convert calendars into numbers, account for leap years, and calculate the difference between dates.

• How to Calculate a Project Deadline

  Step-by-step project deadline calculation: from task breakdown to assembling the final date with risk considerations.

• How to Calculate the Day of the Week for Any Date Mentally

  Learn to determine the day of the week from a date without a calendar! We explain John Conway's algorithm.

• ISO 8601 – The Global Standard for Dates and Time

  Learn what the ISO 8601 standard is, how it solves the problem of different date formats worldwide, and why it is important for global web services.