Days Between Dates
Count the exact days between any two dates — including business days and weekends.
Pick two dates to count the days between them.
The gap between two dates seems like it should be a single number, but it depends entirely on what you are counting. From January 31st to March 1st is 29 days, or one month and one day, or zero months if you insist that a month requires a matching day-of-month that February does not have. None of these is wrong; they answer different questions. This calculator gives you the full picture: total days, weeks, and the calendar-aware breakdown into years, months, and days — plus business days, which is usually the number that actually matters when you are planning a deadline rather than satisfying curiosity.
How the calculator works
Enter a start date and an end date. The calculator returns the total elapsed days, the same interval expressed in weeks, and a calendar-aware breakdown into years, months, and days using the borrowing method. It also counts business days by walking the interval and excluding Saturdays and Sundays. Every leap day within the range is counted automatically, since the calculation works from real calendar dates rather than from an assumed year length.
The methods
Total days = (end − start) ÷ 86,400,000 ms
Weeks = Total days ÷ 7
Business days ≈ (Total days ÷ 7) × 5
... but computed exactly by iterating and
skipping Saturday and Sunday
Calendar breakdown: subtract Y/M/D with borrowingThe two approaches genuinely disagree, and that is not a bug. Total days is unambiguous arithmetic. The calendar breakdown answers the human question, and it is inherently approximate because months have no fixed length — "one month" from January 31st cannot land on February 31st, so a convention must be chosen. Business days are a third question again, and the simple weekday count ignores public holidays, which vary by country and can shift a project deadline by a week during December.
What to know about date intervals
- 1Decide whether your interval is inclusive or exclusive before you count. A project running Monday to Friday is five days if you count both endpoints and four if you count the gap between them. Both readings are defensible, and contracts, invoices, and rental agreements have been argued over precisely this ambiguity.
- 2Business day counts ignore public holidays unless you subtract them yourself. Christmas week alone can remove two or three working days, and if your calculation crosses a country's holiday season, a fifteen-business-day estimate can easily become twenty calendar days in practice.
- 3Leap years are handled automatically here, but they trip up manual math. Any interval spanning February 29th gains a day. Between 2024 and 2028 there are two leap days, so a four-year gap is 1,461 days rather than 1,460 — small, but enough to matter in interest calculations.
- 4Day-of-week patterns repeat on a 28-year cycle in the Gregorian calendar, with disruptions at century marks. This is why your birthday falls on the same weekday in patterns of 6, 11, or 12 years rather than at a regular interval — the leap year rule breaks the symmetry.
- 5For contracts and legal deadlines, verify whether the terms mean calendar days or business days. "Within 30 days" and "within 30 business days" differ by roughly two weeks, and that gap is the source of a remarkable amount of dispute.
Frequently asked questions
Does the calculation include both the start and end dates?
The day total measures the interval between the two dates, so a start of January 1st and an end of January 2nd gives one day. If you need an inclusive count — counting both endpoints as full days, which is how event durations and hotel stays are usually described — add one to the result. Which convention is correct depends entirely on what you are measuring.
How are business days counted?
By walking through the interval day by day and counting only Monday through Friday, excluding Saturdays and Sundays. Public holidays are not excluded, since they differ by country and region and there is no universal list. If your interval crosses a known holiday period, subtract those days manually to get a realistic working-day figure.
Why does the month count seem inconsistent?
Because months have no fixed length, so "one month later" is a convention rather than a fact. From January 31st, one month later cannot be February 31st, so the calculation borrows the actual number of days in the relevant month. This means intervals that look similar can produce different month counts depending on which months they cross — genuinely unavoidable, not an error.
Are leap days included?
Yes, automatically. The calculation works from actual calendar dates, so every February 29th within your range is counted. This is why a four-year interval is often 1,461 days rather than 1,460. Manual calculations that multiply years by 365 miss these and drift by a day for every leap year spanned.
Can I calculate the difference including time of day?
This calculator works at the level of whole dates, which is what most planning and deadline questions require. If you need hour-and-minute precision — for billing, SLAs, or elapsed-time measurement — you need a timestamp difference rather than a date difference, and you must account for daylight saving transitions, which silently add or remove an hour from an interval twice a year in many regions.