Date calculator
This date calculator adds or subtracts days, weeks, months and years from any date, or counts the days between two dates. Turn on business days to skip weekends and, if you like, US federal holidays.
- Add or subtract from a date
- Days, weeks, months and years between dates
- Business days with US federal holidays
Last updated
How to use the date calculator
- Choose Add or subtract to find a future or past date, or Days between dates to count the gap between two dates.
- Pick the start date (it starts on today). For a gap, also pick the end date.
- To add or subtract, enter any mix of years, months, weeks and days. Tick Business days only to count working days instead.
- Read the result date or the day count. The figures below it give weeks, months and business days too.
How the date calculator counts
Adding time. Years and months are added first, then weeks and days. If the new month is shorter, the date is moved to its last day: January 31 plus 1 month is February 28 (or 29 in a leap year).
Days between dates. The count is the number of midnights between the two dates, so it does not count the start date:
days between = end date − start date
From March 1 to March 10 is 9 days. Tick “Count both the start and end dates” to get 10, which is how many calendar days the period covers.
Business days are Monday to Friday. With US federal holidays turned on, the 11 holidays in 5 U.S.C. 6103 are skipped on their observed dates: a holiday on a Saturday is observed the Friday before, and one on a Sunday the Monday after. Dates are handled in UTC, so daylight saving time never adds or loses a day.
Worked example
What date is 90 days after October 28, 2026?
- October has 31 days, so 3 days remain after the 28th. That leaves 90 − 3 = 87 days.
- November uses 30 days: 87 − 30 = 57 days left.
- December uses 31 days: 57 − 31 = 26 days left.
- So the answer is January 26, 2027, a Tuesday.
Counting 10 business days from Friday, November 20, 2026, with federal holidays skipped: the weekdays are Nov 23, 24, 25, 27 (Thanksgiving, Thursday Nov 26, is skipped), 30, and Dec 1, 2, 3, 4 and 7. The 10th business day is Monday, December 7, 2026.
US federal holidays 2026 and 2027
These are the observed dates the business-day option skips, from the U.S. Office of Personnel Management. Last checked 28 October 2026.
| Holiday | 2026 | 2027 |
|---|---|---|
| New Year’s Day | Thu, Jan 1 | Fri, Jan 1 |
| Martin Luther King Jr. Day | Mon, Jan 19 | Mon, Jan 18 |
| Washington’s Birthday | Mon, Feb 16 | Mon, Feb 15 |
| Memorial Day | Mon, May 25 | Mon, May 31 |
| Juneteenth | Fri, Jun 19 | Fri, Jun 18 (observed) |
| Independence Day | Fri, Jul 3 (observed) | Mon, Jul 5 (observed) |
| Labor Day | Mon, Sep 7 | Mon, Sep 6 |
| Columbus Day | Mon, Oct 12 | Mon, Oct 11 |
| Veterans Day | Wed, Nov 11 | Thu, Nov 11 |
| Thanksgiving Day | Thu, Nov 26 | Thu, Nov 25 |
| Christmas Day | Fri, Dec 25 | Fri, Dec 24 (observed) |
State holidays, bank holidays and your employer’s own days off are not included. Juneteenth is counted from 2021, the first year it was a federal holiday.
Days in each month
| Month | Days | Month | Days |
|---|---|---|---|
| January | 31 | July | 31 |
| February | 28 (29 in leap years) | August | 31 |
| March | 31 | September | 30 |
| April | 30 | October | 31 |
| May | 31 | November | 30 |
| June | 30 | December | 31 |
A leap year is divisible by 4, except century years, which must be divisible by 400. 2028 is a leap year; 2100 is not. A common year has 365 days and a leap year 366.
Common questions
How do I count the days between two dates?
Subtract the earlier date from the later one. From January 1 to March 1, 2026 is 31 + 28 = 59 days. Add 1 if you want to count both the first and last day.
What date is 90 days from today?
Pick today’s date, choose Add and enter 90 days. From October 28, 2026, 90 days later is Tuesday, January 26, 2027.
How do I calculate business days between two dates?
Count only Monday to Friday, and skip holidays if your deadline does. November 2026 has 21 weekdays, or 19 business days once Veterans Day and Thanksgiving are taken out.
What is 6 months from a date?
Add 6 to the month and keep the same day. April 15 plus 6 months is October 15. If that day does not exist, the last day of the month is used: August 31 plus 6 months is the end of February.
How many weeks are between two dates?
Divide the number of days by 7. 100 days is 14 weeks and 2 days. The calculator shows weeks and days under every result.
Does the date calculator count the start date?
Not by default. Days between dates counts the days after the start date up to the end date, the usual way to measure a gap. Tick the option to count both dates for an inclusive count.
Related calculators
- Time calculatorAdd, subtract, multiply or divide hours, minutes and seconds
- Military time converterConvert 24-hour military time to 12-hour AM/PM time and back
- PTO accrual calculatorPTO earned per hour worked and per paycheck, with your future balance
- Hours calculatorHours and minutes between two times, with breaks and overnight shifts
Sources
- 5 U.S.C. 6103, Holidays. The 11 legal public holidays
- U.S. Office of Personnel Management, Federal Holidays. 2026 and 2027 observed dates and the Saturday/Sunday rule
See the methodology page for how Clockfigure builds and checks its calculators.