Date Difference Calculator

// One span, four ways of saying it

The gap between two dates has more than one true answer, and which one you want depends on what the number is for. A total of 90 days is the right answer for a deadline written in days. Twelve weeks and six days is the right answer when the thing recurs weekly. Two months and 28 days is how a person would describe it out loud. Sixty-four working days is the right answer when the count is meant to exclude weekends. All four describe the same stretch of calendar, so this calculator shows all four rather than making you pick up front.

The years-and-months form is the one worth reading carefully, because months are not a fixed length. This tool counts whole months first and measures whatever is left in days, so January 31st to March 1st is one month and one day. Adding a month to January 31st lands on the last day of February — there is no February 31st to land on — and the remaining day takes you to March 1st. Any tool that instead subtracts the day numbers and borrows has to explain a negative remainder, and most of them do it by quietly producing the wrong number.

// Whether the dates themselves count as days

The single most common disagreement about date arithmetic is whether the last day is included. Left off, the count measures the distance between the two dates: from the 1st to the 8th is seven days, which is what you want when working out when something falls due. Switched on, the count measures days occupied — both dates included: the 1st to the 8th becomes eight days, which is what a hotel bills you for, what a notice period covers, and what a leave request consumes.

The toggle makes the choice explicit instead of picking one and hoping. When it is on, every figure on the panel moves together — the total, the weeks, the years and months, and the working-days count all describe the same extended span. A tool that applied the setting to the headline number and forgot the working-days count would show two figures that quietly contradict each other, which is the failure this design exists to avoid.

// Working days, without inventing your holidays

The working-days figure counts Mondays through Fridays in the span and reports weekend days separately. It is not simply five-sevenths of the total: which weekday the span begins on decides how the leftover part-weeks fall, so two 90-day spans starting a few days apart can differ by two working days. That is why the count is worth having rather than estimating.

Public holidays are never deducted. They differ by country, by state or province, by industry, and year to year for every holiday tied to a lunar or ecclesiastical calendar. Subtracting a guess would produce a number that looks authoritative and is wrong for most visitors, so the tool counts weekdays, says so on the row itself, and leaves the holiday adjustment to you — where the knowledge actually is.

// Dates in either order, and dates a long way apart

The two dates can go in either order. If the end date is earlier than the start date, the span is reported as the same positive count with the direction stated, rather than as a negative number — minus 90 days is a shape, not an answer, and it is the form most likely to be pasted somewhere it will be misread.

The arithmetic works on calendar dates with no time attached, which is what keeps daylight-saving transitions out of the result. Tools that subtract two timestamps and divide by 86,400 are counting fixed-length days, and in a year that loses an hour in spring that division does not land on a whole number — so the answer gets rounded, and the rounding goes a different way depending on which side of the year you are on. There is no hour here to lose, so the count is exact for spans of any length, including ones that cross a leap day or a century.

Nothing is uploaded. The dates you type stay in the page, no request is made when you change them, and the calculator keeps working with the network disconnected.

// fair questions

How many days are between two dates?

Enter both dates above and the total appears immediately, along with the span in weeks, in years and months, and in working days. By default the count is the distance between the dates — from the 1st to the 8th is seven days — and the toggle switches it to counting days occupied instead.

Should I count both dates or not?

Leave it off when you are measuring the distance to a deadline; switch it on when you are counting days you occupy or are charged for, like a hotel stay or a notice period. The difference is exactly one day, and every figure on the panel moves together when you change it. It counts both of the dates you entered, whichever order you entered them in.

Does the working-days count exclude public holidays?

No, and that is deliberate. It counts Monday to Friday and reports weekend days separately. Public holidays vary by country, by region within a country, and from year to year, so any deduction would be a guess dressed up as an answer. Subtract your own holidays from the weekday count.

Can the second date be earlier than the first?

Yes. The span is reported as a positive count with the direction named rather than as a negative number, because a figure like −90 days is easy to misread once it has been copied somewhere else.

Why does the years-and-months figure not match my own arithmetic?

Months are between 28 and 31 days long, so the answer depends on the order the units are counted in. This tool counts whole months first, then the leftover days, which is why January 31st to March 1st reads as one month and one day: one month from January 31st is February 28th, and one more day gets you to March 1st.

Is the leap day counted?

Yes. Any February 29th inside the span is counted as a day like any other, which is why two otherwise identical spans in different years can differ by one day.

Do the dates I enter leave my browser?

No. The whole calculation runs locally, nothing is sent to a server, and nothing is stored or logged. Once the page has loaded it works offline.