Date Calculator
Find the days, weeks, or years between two dates, or add/subtract days from a date.
How the calculation works
In 'days between' mode, this finds the exact number of calendar days between two dates, plus a calendar breakdown into whole years, months, and days (the same shape as an age calculation), and shows weeks and remaining days too. Exclusive counting (the default) counts the span between the two dates; inclusive counting adds one day to also count both the start and end day themselves, which matters for things like 'how many days is a vacation from Monday through Friday' (5 inclusive, 4 exclusive). In 'add or subtract' mode, this adds a number of days to a start date, or subtracts them if you enter a negative number, to find the resulting date.
Formula
Days Between = End Date − Start Date, in calendar days (add 1 for inclusive counting). Add/Subtract = Start Date + Days to Add, where a negative number subtracts.
Examples
Days between Jan 1, 2026 and Aug 10, 2026 (exclusive)
221 days (31 weeks, 4 days); 7 months, 9 days
90 days after Aug 10, 2026
Nov 8, 2026