Math
Days between two dates, or add and subtract days from a date.
Result
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Enter dates above
Planning a project that starts January 15 and needs to finish 90 days later? Switch to "Add or subtract days," enter January 15 and 90 days, and get April 15 instantly — accounting for the actual number of days in January, February, and March, rather than a rough "three months later" guess that could be off by several days.
Counting days on a calendar by hand is error-prone specifically because months don't have a consistent length and leap years add an extra day roughly every four years — both easy to miscount manually, especially across a date range spanning several months. A calculator applied to real calendar arithmetic removes that risk entirely.
Use the "Days between two dates" tab, enter a start and end date, and the calculator counts every day between them, including a total in weeks.
Switch to the "Add or subtract days" tab, pick a starting date, enter how many days, and choose whether to add or subtract — useful for deadlines, due dates, or contract terms.
Yes — the calculation works directly with real calendar dates, so leap years and varying month lengths are handled automatically.