Add or subtract time from any date
Choose a start date, enter a whole-number amount, and add or subtract days, weeks, months, or years. The answer includes the target date, weekday, and the number of calendar days actually crossed.
30 days from a date
If the start date is August 14, adding 30 calendar days gives September 13. This calculator uses calendar days, so weekends count. Use the Business Days Calculator when weekends should be skipped.
What happens at the end of a month?
When adding months or years, the calculator preserves the day of month when possible. If the target month is shorter, it uses the last valid day. For example, one month after January 31 is the last day of February.
Calendar days versus business days
This page performs ordinary calendar arithmetic. It does not skip weekends or holidays. For workday deadlines, use the dedicated business-day tool so the non-working-day assumptions stay visible.
Common questions
Can I subtract days from a date?
Yes. Choose Subtract and enter the number of days, weeks, months, or years to move backward.
Does adding one month always mean 30 days?
No. Calendar months vary in length. Month arithmetic moves to the corresponding calendar month and clamps to its last valid day if necessary.
Can I find the number of days between two dates?
Use the Days Between Dates Calculator for elapsed date differences.