You can use these calculators to calculate days between two dates, event time, convert calendars, and more..

A PERSIAN CALENDAR CALCULATOR
NetNative

Calculator: Add to or subtract from a date
This service enables you to add or subtract days, months and years to a date to calculate a past or future date.

Calendar Converter
This page allows you to interconvert dates in a variety of calendars, both civil and computer-related.

Date Duration Calculator: Days between two dates
This service calculates the duration, counting the day count and the number of days, months and years between two dates. Among other things, it can be used find how many days old you are and the weekday you were born.

Event Time Announcer – setup
The Event Time Announcer converts the time of your planned event to local times all over the world for easy sharing and broadcasting.