Handitab

Date Calculator

Add or subtract years, months, weeks, and days from a starting date to find the resulting date and its day of the week.

About Date Calculator

Date arithmetic moves a calendar date forward or back by a set period. This calculator applies years, months, weeks (as 7 days each), and days in a single step, then normalizes the result to a real calendar date. If the target month is too short for the day number, the extra days roll into the next month. It shows the result in long form, in ISO format (YYYY-MM-DD), and as a number of days from the start.

How to use Date Calculator

  1. Fill in "Start date", "Operation", "Years" and "Months", and the other options.
  2. The result appears below and updates as you type.
  3. Copy the result with the copy button, or download it as a file where that is offered.

Questions about Date Calculator

What is one month after January 31?

February has no 31st, so the extra days roll over: the result is March 3, or March 2 in a leap year. If you need the last day of February, subtract the overflow days manually.

Runs in your browser. Page last updated .

More time and date tools

All 25 time and date tools
Days Between Dates CalculatorCalculate the time between two dates in days, weeks, months, and years, with an option to count the end date as well.Exam TimerStart a 90 minute exam timer with large digits and a progress bar, adjust the length to your paper, and hear a beep at the end.Hours CalculatorCalculate the hours worked between a start time and an end time minus an unpaid break, with optional pay from an hourly rate.How Many Days Until Christmas?See how many days, hours, minutes, and seconds are left until Christmas Day, December 25, counted live in your local time.How Many Days Until Halloween?See how many days, hours, minutes, and seconds are left until Halloween, October 31, counted live in your local time zone.Military Time ConverterConvert a time between the 24-hour clock, military time such as 1530, and the 12-hour clock with AM or PM.