Date Calculator
This date calculator answers: how many days until a date? From 1 November 2026 to Christmas Day there are 54 days, and 90 days after 15 January 2026 is 15 April 2026. What date is 90 days or 20 business days from now? Pick a mode, enter a date and get the result instantly, with the steps shown. Leave the start date empty to count from today. It also works as a deadline calculator: a start date plus a number of days or business days gives the due date.
Source: ISO 8601 – Date and time format (Gregorian calendar, weeks). Updated: .
How it is calculated
Three calculations in one date calculator
- Days between two dates: the difference in days, in years, months and days, and in weeks. Counting runs from day to day – 27 September to 28 September is 1 day. To count both days (for example days of a trip or of leave), tick “Include the end date”.
- Add or subtract days, weeks, months, years: days and weeks are simply counted on. For months and years the day of the month stays the same (15 November + 3 months = 15 February). If that day does not exist in the target month, the last day of the month is used: 31 January + 1 month = 28 February (29 February in a leap year), 31 January + 2 months = 31 March.
- Add or subtract business days: weekends and the public holidays of the selected country are skipped. Choose a state or region for regional holidays; without one only nationwide holidays count.
Examples
From 27 September 2026 to Christmas Eve, 24 December 2026, there are 88 days – 2 months and 27 days, or 12 weeks and 4 days. From 1 January 2026 to 24 December 2026 there are 357 days, 358 including the end date.
How to calculate days between dates
- Under “What do you want to calculate?”, pick days between two dates, add/subtract days, weeks, months, or add/subtract business days.
- Enter the start and end date, or an amount and unit; for business days, choose the country whose public holidays apply.
- Read the result and the steps. Tick “Include the end date” if the last day should count.
Example: From 1 March to 31 December 2026 there are 305 days, or 306 including the end date – that is 43 weeks and 4 days.
Business days around Thanksgiving: Wednesday, 25 November 2026 + 1 business day in the United States gives Friday, 27 November 2026 (Thanksgiving on 26 November is skipped). Around Easter in Germany (North Rhine-Westphalia): Thursday, 2 April 2026 + 1 business day = Tuesday, 7 April 2026, skipping Good Friday, the weekend and Easter Monday.
Worked examples, 2026 and 2027
| Calculation | Result | Detail |
|---|---|---|
| 1 Nov 2026 to 25 Dec 2026 | 54 days | 1 month 24 days, 7 weeks 5 days; 40 weekdays, 14 weekend days |
| 1 Jan 2027 to 15 Apr 2027 (Thursday) | 104 days | 3 months 14 days, 14 weeks 6 days |
| 29 Oct 2026 to 1 Jan 2027 | 64 days | 2 months 3 days, 9 weeks 1 day |
| 4 Jul 2026 to 4 Jul 2027 | 365 days | exactly 1 year (52 weeks 1 day) |
| 1 Jan 2027 to 31 Dec 2027, end date included | 365 days | the whole year; without the end date it is 364 |
| 15 Jan 2026 + 90 days | Wed 15 Apr 2026 | days are simply counted on |
| 1 Mar 2027 − 45 days | Fri 15 Jan 2027 | February 2027 has 28 days |
| 2 Nov 2026 + 6 weeks | Mon 14 Dec 2026 | 6 × 7 = 42 days |
| 31 Jan 2027 + 1 month | Sun 28 Feb 2027 | day 31 does not exist in February, so the last day is used |
| 29 Feb 2028 + 1 year | Wed 28 Feb 2029 | 2029 is not a leap year |
US federal holidays follow 5 U.S.C. § 6103; the dates, including the weekend rule, are listed by the U.S. Office of Personnel Management. In 2026 Thanksgiving is on Thursday, 26 November; in 2027 on Thursday, 25 November, and because 25 December 2027 is a Saturday, Christmas is observed on Friday, 24 December.
Common mistakes
- Counting the end date by accident: 1 January to 31 December 2027 is 364 days by default, 365 with “Include the end date”.
- Adding 30 days instead of one month: 31 January 2027 + 30 days is 2 March 2027, but + 1 month is 28 February 2027.
- Reading 04/05/2027 the wrong way round: in the US this is April 5, elsewhere 4 May. Enter the date in an unambiguous form such as 2027-04-05.
- Forgetting holidays when counting business days: 20 weekdays are four weeks, but a holiday in between moves the due date by a day.
- Assuming a year is always 365 days: 29 Feb 2028 exists, so 1 Jan 2028 to 1 Jan 2029 is 366 days.
Holiday data and weekends
For more than 240 countries the public holidays come from the open-source python-holidays dataset, cross-checked against Nager.Date; only the data of the selected country is loaded. The data currently covers 2026 and 2027 – outside those years only weekends are skipped and the calculator shows a notice. German holidays are calculated from the state holiday laws for any year. The weekend depends on the country (for example Friday and Saturday in Saudi Arabia). Dates follow the Gregorian calendar as in ISO 8601.
Date calculator, time calculator or age calculator?
The date calculator works with whole calendar days. For a time span with clock times (hours, minutes, daylight saving time) use the time calculator; for someone's age from the date of birth use the age calculator.
Also useful: the countdown timer counts down live to an event, the working days calculator lists business days per month, and the time zone converter helps with deadlines across countries.
Frequently asked questions
How do I use this as a deadline calculator?
Enter the start date, then choose “Add/subtract days, weeks, months” for a deadline in calendar days or “Add/subtract business days” to skip weekends and public holidays. The result is the due date with its weekday. The start date itself is not counted; for legal deadlines, check which counting rule applies to your case.
How many days until a date?
Choose “Days between two dates”, leave the start date empty (= today) and enter the target date. From 27 September 2026 to 24 December 2026 there are 88 days.
Is the end date included?
Not by default: counting runs from day to day, so 1 January to 2 January is 1 day. Tick “Include the end date” to count both days (2 days) – useful for trips, leave or hotel stays counted in days.
What is 31 January plus one month?
28 February, or 29 February in a leap year. If the day does not exist in the target month, the last day of that month is used. Adding two months gives 31 March again.
What date is 30 business days from today?
Choose “Add/subtract business days”, enter 30 and select your country and, if needed, your state or region. Weekends and public holidays are skipped; the start date itself is not counted.
How do I calculate days between dates in Excel?
Subtract the start date from the end date, e.g. =B1-A1, or use =DAYS(B1,A1). For business days use =NETWORKDAYS(A1,B1).
How many weekdays are there between two dates?
From 27 September to 24 December 2026 there are 64 weekdays (Monday to Friday) and 24 weekend days. For any difference in days, the line “Weekdays and weekend days” counts both separately; public holidays are not deducted – use the business-days mode for that. The line below gives the ISO 8601 calendar week of both dates (here weeks 39 and 52).
How many days are in 2027?
2027 has 365 days because it is not a leap year; 1 January to 31 December 2027 is 364 days, or 365 with the end date included. The next leap year is 2028 with 366 days.
Sources and legal basis
- ISO 8601 – Date and time format (Gregorian calendar, weeks)
- python-holidays – public holiday data by country (MIT licence)
- Nager.Date – public holiday API used as cross-check (MIT licence)
As of: · Editorial policy
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