Date Difference Calculator

Pick a start date and an end date to see the gap as years, months and days — plus total days, weeks and hours. It measures the true number of calendar days between any two dates, runs entirely in your browser, and needs no sign-up.

What is the Date Difference Calculator?

The Date Difference Calculator is a free online tool that measures the true number of calendar days between any two dates and then breaks that span down into the units you actually need. Pick a start date and an end date, and it shows the gap as years, months and days together, plus the total in days, weeks and hours. Unlike an age calculator, which always compares one birth date against today, this tool works on any two dates — a project kickoff and its deadline, the start and end of a trip, the day you signed a lease and the day it expires. It also answers two questions most simple "days between dates" pages ignore: should the final day be counted, and how many of those days are actually working days.

How to use it

Set the start date in the first field.
Set the end date in the second field. It defaults to today from your device clock, so a single date entry already gives you "how long until or since" an event.
Read the answer instantly — the years-months-days breakdown appears with total days, weeks and hours below it.
Flip "Include the end day" when you want both endpoints counted (hotel nights, lease terms, notice periods).
Glance at the business-days figure if you only care about weekdays.

That is the whole flow: two inputs, an immediate answer, and you can close the tab. The order does not matter — enter the later date first and you still get the same positive result.

The method behind it

Counting a span between dates is not as simple as subtracting two years, because months and years have different lengths. The calculator uses a calendar-borrowing method for the years-months-days view:

Subtract the start year from the end year for a first estimate of whole years.
Compare the months. If the end month is earlier, subtract one year and add 12 months.
Compare the days. If the end day is earlier, borrow the real length of the previous calendar month (28, 29, 30 or 31, leap years included) and reduce the month count by one.

For the total figures, the tool takes the millisecond delta between the two midnights and converts it to whole days, so leap days are already baked in — there is no "× 365" shortcut. Weeks are days divided by 7 (with the remainder shown separately) and hours are days times 24. The include-end-day toggle simply adds one to the total, and the business-days count walks the range one day at a time, keeping only Monday through Friday and skipping every Saturday and Sunday. It does not remove public holidays, since those differ by country, so treat it as a weekday count.

Worked example

From 3 March 2026 to 18 June 2026, with the end day not counted:

Breakdown: 3 months, 15 days.
Total days: 107. Total weeks: 15 weeks and 2 days. Total hours: 2,568.
Business days: 77, after the weekends are removed.

Turn on "include the end day" and the total becomes 108 days, while the business-day count rises to 78 because 18 June is a Thursday.

Common use cases

Deadlines and countdowns — how many days are left until a launch, exam or filing date.
Contracts, leases and subscriptions — measuring a term, often with the end day included.
Travel — the length of a trip, or days spent in a country for visa or tax day-counting.
Project planning — working days between a start and a due date, weekends excluded.
Billing and notice periods — counting whole days or weeks for invoices, refunds or resignations.

Why use this one

Many "days between dates" pages return a single total-days number and stop there. This one gives the full years-months-days breakdown next to the total days, weeks and hours in one view, adds an include-end-day toggle for the off-by-one cases that trip people up, and throws in a weekday-only business-days count. It runs entirely in your browser using your device clock, so both dates stay on your device, there is no account, and the answer appears the instant two valid dates are set.

It sits in a small cluster of everyday date tools. To turn a birth date into an exact age, use the Age Calculator; to count down to a future date and time live, use the Countdown Timer; and to translate between Unix epoch seconds and readable dates, the Unix Timestamp Converter does it in both directions.

Frequently asked questions

How do I calculate the number of days between two dates?

Choose a start date and an end date in the two fields. The tool reads them against your device clock and instantly shows the exact number of calendar days between them, along with the same span expressed in years, months and days, total weeks, and total hours.

What does the include-end-day option do?

By default the end day is not counted, so 1 January to 2 January is 1 day. Turn on include the end day and both endpoints are counted, making the same range 2 days. This matches how hotel nights, lease terms and notice periods are often counted.

How are business days counted?

The business-days figure counts only Monday through Friday in the range and skips every Saturday and Sunday. It does not subtract public holidays, since those vary by country and region, so treat it as a weekday count rather than an official working-calendar count.

Does it handle leap years correctly?

Yes. The total number of days comes straight from the calendar, so February 29th and leap years are included automatically. There is no rough multiplication by 365 anywhere in the math, which is why the total can differ from a quick estimate.

Are my dates sent anywhere or stored?

No. The whole calculation runs locally in your browser using your device clock. The two dates you enter are never uploaded, saved or shared, and no account is required.

What if I enter the dates in the wrong order?

It does not matter. The tool always measures the gap from the earlier date to the later one, so you get the same positive result whether you put the bigger date first or second.