Two everyday date jobs in one place: count the days between two dates, or work out the date a set number of days, weeks, months, or years from a start date.
Days between two dates
Add or subtract from a date
How many days are there between two dates? Subtract the earlier date from the later one. The catch is month lengths and leap years — February has 29 days in a leap year (every 4 years, with exceptions at century marks). The counter above handles all of that exactly.
Should the start and end days both count? It depends on the job. Deadlines and date differences usually exclude the start day; counting nights of a stay or days of an event usually includes both ends. The checkbox lets you choose — it changes the result by one day.