How to use this reference
Calendar months have different lengths, so dividing a day count by 30 is not a reliable month calculation. This tool counts full calendar-month steps and then the remaining days. Use it for approximate planning around renewals, course dates or milestones, rather than contracts that specify a different day-count convention.
Month addition preserves the day of the month when possible and clamps it to the final day when necessary. January 31 plus one month is February 28 in a common year and February 29 in a leap year, not a date in March. A direct two-month addition still uses the original anchor rather than repeatedly adding one clamped month.
Today is taken from your local browser calendar and updates while this page stays open. For fixed seven-day intervals use the Weeks Until/Since Calculator. For exact elapsed calendar days use the Day Counter; the Leap Year Calculator explains why February’s length changes.
Frequently asked questions
Is one month treated as 30 days?
No. The calculation uses calendar months and their actual lengths, with leftover calendar days shown separately.
What happens when a target month has no 31st?
The date is clamped to the last valid day of that month, such as February 28 or February 29.
Are month additions always reversible?
No. Clamping can lose the original day: January 31 plus one month becomes February 28, and subtracting a month from that date gives January 28.