Question 1

How do I add or subtract days from a date?

Accepted Answer

Enter a start date — in the Shamsi (Jalali) or Gregorian calendar — choose Add or Subtract, then set the number of years, months, weeks and days. Timeyard shows the resulting date in both calendars, with the weekday and the total day offset. Everything is calculated on your device.

Question 2

Does the calculator handle the Persian (Shamsi) calendar correctly?

Accepted Answer

Yes. The start date has a Shamsi / Gregorian toggle. Years and months are added within your chosen calendar — so a Jalali “+1 month” lands on the next Jalali month — with correct month-length clamping (for example a date on the 31st rolling into a 30-day month, and Esfand in leap years). Weeks and days are counted as exact days.

Question 3

What happens when a month is shorter than the start day?

Accepted Answer

The result is clamped to the last valid day of the target month. For example 31 January plus one month becomes 28 February (or 29 February in a leap year), and the same rule applies to Esfand in the Jalali calendar.

Add or subtract from a date جمع و تفریق تاریخ