Days Between Dates Calculator
Pick two dates to count the days between them, shown as total days, weeks, and a years/months/days breakdown. Choose whether to include the end day.
By default the count excludes the end day (the gap between the dates). Switch to “include end day” to count both the start and end dates.
How to use this calculator
Choose a start date and an end date using the date pickers. The calculator instantly shows the total days between them, the equivalent in weeks (and remaining days), and a human-readable breakdown in years, months, and days. Use the "include end date" toggle to switch between an exclusive count (the gap between the dates) and an inclusive count (every calendar day from start through end).
The order of the dates does not matter — the calculator returns the absolute difference, so you can enter the later date first or the earlier date first and get the same result.
How days between dates are calculated
Under the hood, the calculator converts each date to a sequential day number — a method that assigns a unique integer to every calendar date. Taking the difference between two day numbers gives the exact number of calendar days between them, regardless of how many months or years are involved. This approach automatically handles leap years, varying month lengths, and century-year edge cases without any special rules.
The years/months/days breakdown is then derived from that raw day difference by counting how many complete years fit in the span, then how many complete months remain, and finally the leftover days — the same logic used to express age. This breakdown is convenient for understanding large spans ("1 year, 3 months, and 18 days") but is an approximation relative to the exact day count, since months vary in length.
Exclusive vs. inclusive counting: when to use each
The single biggest source of confusion in day counting is whether to include one or both endpoint dates. The two conventions are:
- Exclusive (gap counting): Count the days between the start and end without including the end day itself. This answers questions like "how many days do I have to wait?" or "how many days did the trip last?" (where you leave on day 1 and return on the last day but the trip is over when you arrive home). From January 1 to January 31 is 30 days exclusive.
- Inclusive (range counting): Count every calendar day from start through end, including both. This answers questions like "how many days are in this billing period?" or "how many days is the event running?" From January 1 to January 31 is 31 days inclusive — every day in January.
When in doubt, check what your contract, policy, or agreement specifies. Legal notice periods, rental contracts, and subscription terms can differ on this point.
Worked examples
Example 1: Days until a deadline
Today is June 15 and a project deadline is September 1. Entering these dates (exclusive) gives 78 days remaining — the number of days between now and the deadline without counting September 1 itself. That's 11 weeks and 1 day.
Example 2: Days in a billing period
A monthly subscription runs from May 1 to May 31. Inclusive counting gives 31 days — every day in May. Exclusive gives 30 days (May 31 is not counted as a day in the period). Most billing systems use inclusive counting for calendar-month periods.
Example 3: Measuring the past
An event happened on January 20, 2020 and today is June 15, 2026. The exclusive count gives 2,337 days — or 6 years, 4 months, and 26 days. This is the kind of calculation that is tedious by hand but instant with this tool.
Common uses
- Deadlines: Days until a filing deadline, contract expiry, or event date.
- Notice periods: Many employment contracts and leases require 30, 60, or 90 days' notice — count from today to check.
- Age in days: Enter your date of birth and today's date to see your exact age in days, weeks, and months.
- How long ago: Measure how many days have passed since a past event — a purchase, a start date, or a historical date.
- Rental and billing periods: Confirm the number of days in a rental stay or billing cycle.
- Vacation planning: Count the days in a trip, including or excluding travel days.
Common mistakes to avoid
- Choosing the wrong inclusive/exclusive setting. A 30-day notice period starting on June 1 runs through June 30 exclusive (30 days) or through July 1 inclusive — these give different last days. Confirm which convention applies to your situation.
- Expecting month counts to add up precisely. "3 months" is not always 90 days. Three calendar months from January 1 is April 1 (90 days in a non-leap year), but from March 1 it is June 1 (92 days). If an exact day count matters, use days, not months.
- Forgetting that leap years add a day. A span crossing February 29 in a leap year is one day longer than the same nominal span in a non-leap year. This affects multi-year calculations in particular.
- Entering dates in the wrong order and getting confused. This calculator always returns a positive number regardless of date order, so you will not get a negative result — but make sure you know which date is earlier when interpreting the result.
How we calculate this
The day count is computed by converting both dates to an integer day number (a Julian Day Number equivalent) and taking the absolute difference. The years/months/days breakdown is derived from the same day-level difference by peeling off completed years and months in sequence. Including the end date adds 1 to the total. Leap years and varying month lengths are handled by the underlying date arithmetic, not by any fixed approximation.
Frequently asked questions
How do I count the number of days between two dates?
Enter a start date and an end date. The calculator converts both to an internal day count and takes the difference, showing the result as total days, total weeks, and a years/months/days breakdown. You don't need to account for leap years or month lengths — the calculator handles it automatically.
Should I include the end date in my count?
It depends on what you're measuring. Excluding the end date counts the gap — the number of days you have to wait, or how long something lasted before that final day. Including the end date counts every day in the range, including both endpoints. For example, a rental that starts January 1 and ends January 7 is a 6-night stay (excluding end) or 7 days including both dates.
Does the calculator account for leap years?
Yes. Because the calculation works with real calendar dates rather than assuming a fixed number of days per year, February 29 in leap years is counted correctly. A span crossing a leap day will include that extra day automatically.
Can I count days in the past or between past dates?
Yes. You can enter any two dates regardless of order or whether they are in the past or future. The calculator returns the absolute difference, so it works equally well for 'how many days ago was X?' and 'how many days until Y?'
What is the difference between the total days and the years/months/days breakdown?
Total days is the exact count of calendar days between the two dates. The years/months/days breakdown converts that span into human-readable calendar units — for example, 400 days becomes 1 year, 1 month, and approximately 5 days. The breakdown is intuitive for large spans, while the total is more precise for calculations requiring an exact day count.
How do I count only business days (weekdays)?
This calculator counts all calendar days, including weekends and public holidays. To count only weekdays, you would need to subtract the number of weekend days from the total. For an approximate estimate, multiply the total weeks by 5 and add any remaining weekdays. A dedicated business-day calculator handles this more accurately.
Can I use this for a billing or rental period?
Yes. For billing periods, rental durations, and subscription lengths, enter the start and end dates. Whether to include the end date depends on the terms of your agreement. Many rental contracts count the first day and exclude the last (checkout) day, while some billing periods count both endpoints — check your specific terms.
How many days are in a year, and does it matter here?
A common year has 365 days; a leap year has 366. Because this calculator uses real dates rather than an average, it counts the exact number of days in the span you specify. If your span crosses a February 29, that day is included in the count and the total will be one day more than the same span in a non-leap year.