Calculate the number of days between any two dates, or add and subtract days, weeks, or months from any date. Useful for deadlines, countdowns, and planning.
Find days between two dates, or add and subtract time from any date.
The days-between calculation accounts for leap years and the varying lengths of each month, giving you an exact count rather than an approximation. The add/subtract function works the same way — accurately handling month-end rollovers and year boundaries.
Common uses include calculating how many days are left until an event, working out a payment due date, finding the end of a contract or notice period, or checking how long ago something happened.
Calculating the time between two dates, or finding the date a certain number of days from now, is one of those tasks that is easy to get wrong by hand. Months have different lengths, leap years add a day every four years, and it is easy to miscount whether both the start and end dates should be included. This calculator removes the guesswork, giving you the exact number of days between two dates or the result of adding or subtracting days from a chosen date.
The tool works in two directions. In the first mode you enter a start date and an end date, and it returns the number of days between them. This is useful for counting down to an event, working out the length of a project, or measuring how long ago something happened. In the second mode you enter a date and a number of days to add or subtract, and it returns the resulting date — handy for finding deadlines, due dates, or notice periods.
One common source of confusion is whether to count both end dates. The number of days between Monday and Wednesday is two if you count the gaps, but three if you count all the days involved. Which one you want depends on the situation: a hotel stay counts nights (the gaps), while a notice period may count every calendar day. Being clear about what you are measuring avoids off-by-one errors that can matter for contracts and deadlines.
For example, counting from 1 January 2026 to 31 December 2026 gives 364 days between the two dates, or 365 if you include both ends. Need a deadline instead? Add 90 days to 26 August 2026 and you land on 24 November 2026 — handy for a notice period, a return window, or a project milestone. Letting the calculator handle the month lengths avoids the off-by-one slips that catch people out.
Does the calculator account for leap years?
Yes. Leap days are included automatically, so any range that crosses 29 February is counted correctly.
Can I add or subtract days from a date?
Yes. Enter a starting date and the number of days to move forward or backward, and the calculator returns the exact resulting date.
Should I count both the start and end date?
It depends on what you are measuring. Counting the gaps gives the number of nights or full days between; counting every date gives an inclusive total. Decide which fits your purpose.