Date calculator.
Count the days between two dates — or jump forward and back from one.
Add or subtract days
Counting days the right way
The first tool counts the whole days from the start date to the end date — the gap between them, so the same day start and end is zero days, and a deadline "in 30 days" is 30 days after today. The week and month figures are derived from that day count; months and years are approximate because calendar months vary in length (the calculator uses 30.44 days per month and 365.25 per year, the long-run averages). The second tool runs the other direction: give it a date and a number of days and it returns the resulting calendar date, which is the quick way to find a deadline, a due date, or a "90 days from now" milestone. Use a negative number to go backwards. For an exact age from a birth date, the age calculator breaks it into years, months and days.
Inclusive counts, business days and leap years
A worked example: from March 1 to March 15 the tool returns 14 days, because it counts the gaps between dates, not the dates themselves. If you need an inclusive span — counting both the first and last day, the way a hotel counts nights plus one, or a project counts "day 1" through "day 15" — add one to the result: 14 becomes 15. That single adjustment is the most common source of off-by-one errors in deadlines and invoices.
The calculator counts every calendar day, so weekends and public holidays are included; for a working-days figure, subtract two per full week. Leap years are handled automatically — 2024 and 2028 have a February 29 — so any span crossing late February in those years picks up the extra day without you doing anything.