Days between two dates
The number of days between two dates is the later date minus the earlier one, counted in whole calendar days. From 2024-02-28 to 2024-03-01 in 2024 that is 2 days, because 2024 has a February 29. The same two calendar dates in 2025 are 1 day apart. Counting this way, the same date to itself gives 0 days. Many people also want to count both the first and the last day, for example when a booking includes the day of arrival and the day of departure. Switch that option on and the first example becomes 3 days and a single date becomes 1 day. Because the inclusive count only makes sense when the end date is on or after the start date, the calculator asks you to swap the dates instead of guessing what a negative inclusive count would mean.
If the end date comes first and the inclusive option is off, the calculator shows the difference as a positive number of days and tells you the order is reversed, with the signed value. A whole year from 2026-01-01 to 2026-12-31 is 364 days, or 365 when both ends are counted. The result is also given in weeks and days, and as years, months and days. For the span from 2020-01-31 to 2024-03-01, that is 4 years, 1 months and 1 days: whole months are added from the earlier date first, and the days left over are counted last.
Adding and subtracting years, months, weeks and days
Days and weeks are fixed lengths, but months and years are not, so the order of the steps matters. The calculator applies years and months first and weeks and days second. When a month is shorter than the day you started on, the result moves back to the last day of that month. January 31, 2024 plus one month is Thursday, February 29, 2024, because February 2024 has 29 days, while January 31, 2025 plus one month is Friday, February 28, 2025. Adding a year to February 29 gives Friday, February 28, 2025, since the following year has no February 29.
The order changes the answer in some cases. Starting at 2024-01-30 and adding one month and one day, the calculator moves to the end of February first and then adds the day, reaching 2024-03-01. Adding the day first and then the month would land on February 29. Subtracting is not the exact reverse of adding either: 2024-03-31 minus one month is 2024-02-29, and adding a month back gives 2024-03-29, not the original date. Both behaviours follow from the end-of-month rule, and the result panel states when a date has been moved so it never happens silently. As a simple planning example, six weeks after 2026-11-05 is Thursday, December 17, 2026.
Business days
Business days are the days that are not weekend days, and you choose which days those are. The default is Saturday and Sunday, but you can tick any combination, such as Friday and Saturday, or none. When you add business days, the start day is not counted: you step forward one working day at a time. From Friday 2026-11-06, one business day later is Monday, November 9, 2026, because the weekend is skipped. With a Friday and Saturday weekend the same step lands on Sunday, November 8, 2026. Adding 10 business days from the same Friday gives Friday, November 20, 2026. Adding 0 business days returns the start date, even when it is a weekend: Saturday, November 7, 2026.
To count business days between two dates, the start date is excluded and the end date is included, so a count from Monday to the following Monday is five days. From 2026-11-02 to 2026-11-09 the calculator finds 5 business days. Subtracting works the same way in the other direction, and a count with the end date before the start date is shown as negative.
Excluded dates and holidays
There is no built-in holiday calendar. Holidays differ by country, region and employer, and a list that looked right once can be wrong a year later, so you type the dates you want skipped. Enter them as year-month-day, separated by spaces, commas or new lines. Those dates are treated like extra weekend days. If Monday 2026-11-09 is excluded, one business day after Friday 2026-11-06 becomes Tuesday, November 10, 2026. In the count from the second to the ninth of November, excluding Wednesday the fourth lowers the total from 5 to 4. A date typed twice counts once, and an excluded date that falls on a weekend changes nothing, because the day was already skipped.
Leap years and the supported range
The Gregorian calendar adds a leap day when the year is divisible by 4, except for century years, which must be divisible by 400. That makes 2000 and 2024 leap years, and 1900 and 2100 are not. The calculator uses that rule for every date from January 1, 1900 to December 31, 2100, and shows a clear message if an input or a result falls outside that range instead of giving a wrong date. Dates are whole calendar days, so there are no time zones, no clock times and no daylight saving effects to account for. If you need hours and minutes, the hours between times calculator works with clock times, and the time card calculator totals a week of shifts.
Worked examples
| Question | Answer |
|---|---|
| Days from 2024-02-28 to 2024-03-01 | 2 (3 counting both days) |
| 2024-01-31 plus 1 month | 2024-02-29 |
| 2025-01-31 plus 1 month | 2025-02-28 |
| Friday 2026-11-06 plus 1 business day | 2026-11-09 |
| The same, with Monday 2026-11-09 excluded | 2026-11-10 |
| Business days from 2026-11-02 to 2026-11-09 | 5 |
What this calculator does not do
This calculator is a planning aid. It does not know about public holidays, bank closures or the rules in a contract, so it cannot confirm a legal deadline, a notice period or a delivery promise. Those rules may count days differently, for example by excluding the first day or by moving a deadline that falls on a weekend. Check the exact wording that applies to you, and use the explanations on the result panel to compare conventions.
Date calculator questions
How many days are there between two dates?
Enter both dates and the calculator subtracts them. From 2026-01-01 to 2026-12-31 there are 364 days, or 365 if you count both the first and the last day.
What is the difference between inclusive and exclusive counting?
Exclusive counting is the plain difference between the dates. Inclusive counting also counts the first day, so it is always one more. Use inclusive for stays, bookings and periods where both ends are part of the span.
What is 30 days or 6 weeks from today?
Choose Add or subtract, press Use today to fill in the start date, enter 30 days or 6 weeks and calculate. The result panel shows the date and its weekday.
How do I count business days between two dates?
Choose Business days, pick the option to count between two dates, tick the days that are your weekend and add any holidays you want skipped. The start day is excluded and the end day is included.
Why does adding a month to January 31 give February 28 or 29?
February is too short to have a 31st. The calculator moves the result to the last day of the month, which is the 29th in a leap year and the 28th otherwise.
Does it include public holidays?
No. Type the holidays you want skipped into the excluded dates box. You stay in control of which days count, and the calculator never uses an out-of-date list.