Number of days between March 19th, 2019 and June 18th, 2019
The total number of days between Tuesday, March 19th, 2019 and Tuesday, June 18th, 2019 is 91 days.
This is equal to 2 months and 30 days.
This does not include the end date, so it's accurate if you're measuring your age in days, or the total days between the start and end date. But if you want the duration of an event that includes both the starting date and the ending date, then it would actually be 92 days.