Date Difference Calculator
How long between two dates, expressed in every unit you might need.
How it works
The gap between two dates is reported two ways, because there are two honest answers. The total in days is a plain count of elapsed days. The breakdown into years, months and days walks the calendar forward one unit at a time, which is how people describe durations in speech but which cannot be converted back into a day count without knowing the start date.
Counting is exclusive of the start date by default: 1 January to 2 January is one day. Many contracts and court rules count inclusively, making the same span two days, so an inclusive option is provided. Which convention applies is a legal question rather than an arithmetic one.
Dates are handled as civil dates anchored to UTC midnight, so a clock change inside the range cannot add or remove a day.
Examples
Days until a deadline. From 1 January 2026 to 11 August 2026 is 222 days, or seven months and ten days. Both describe the same span.
A notice period counted inclusively. Christmas Day to New Year's Day is six days exclusive and eight days inclusive of both ends — the difference that decides whether a deadline lands before or after a holiday.
Working out an anniversary. Enter a past date and today to see the elapsed span in whole years and months, which is the form most people want for length of service.
Practical notes
Decide up front whether your count includes both endpoints. Legal notice periods and court rules frequently do; everyday speech does not. The same pair of dates can legitimately be described as six days or eight, and the difference decides whether a deadline falls before or after a weekend.
The years-months-days breakdown and the total in days are both correct and are not interchangeable. A month is not thirty days, so you cannot convert one figure into the other without knowing the start date.
For anything involving working days rather than calendar days, the business days calculator is the right tool — it excludes weekends and any holidays you supply, which this one deliberately does not.
Frequently asked questions
Why do the month and day figures not simply divide?
Because months have different lengths. The day count is exact; the “months and days” figure is the calendar description of the same gap.
Are leap days included?
Yes. Any 29 February inside the range is counted like any other day.
Does it work with dates in the past?
Yes, in either order. If the end date is earlier, the result notes it and the count is still given as a positive number.
Should I count the first day?
It depends on the rule you are working to. Notice periods and court deadlines frequently count both endpoints; ordinary usage does not. The inclusive option covers the first case.
Why do the months and the day count disagree?
They measure different things. A month is between 28 and 31 days, so a span of three months is not a fixed number of days. Both figures are correct answers to different questions.
Does it count weekends?
Yes, every calendar day is counted. For working days only, use the business days calculator.
Can I compare dates in different years?
Yes, and across centuries. Leap days inside the range are counted correctly.
Why is the result one day off what I expected?
Almost always the inclusive question — whether both endpoints count. Toggling that option usually reconciles the two figures.
Does it handle times as well as dates?
It works on whole calendar dates. For a duration measured in hours and minutes, use the time duration tool.
Can I include the end date?
Yes, the inclusive option counts both endpoints, which matches most contractual language.
How many days are there in a year?
365, or 366 in a leap year. That is why a span of "one year" in days depends on which year it crosses, and why the calendar breakdown and the day count answer different questions.
Can I work out someone's age with this?
You can, though the age calculator is better suited: it reports completed years, months and days in the form people actually use, and handles leap-day birthdays explicitly.