Pick a start date and a number of days, weeks, months, years or weekdays, and this free add days to date calculator counts forward or backward. It shows the result with its day of the week and how many calendar days away it is, so you can find a deadline, a due date, a trip date or what falls 100 days from today in seconds.
Quick answer: to subtract days from a date, type a minus sign before the number, such as -30. To count only Monday to Friday, choose weekdays as the unit.
How to use the add days to date calculator
- Choose the start date. It is set to today, so the result is a number of days from today unless you change it.
- Type how many to add, from −100,000 to 100,000. Use a minus sign to go back in time.
- Choose the unit: days, weeks, months, years or weekdays (Monday to Friday).
The add days to date calculator shows the full date with its day of the week and the number of calendar days between the two dates. Everything is worked out in your browser, so nothing you enter is saved.
Date examples and a printable 100-day tracker
The cards show 100 days from a date, how months and years are added and how business days skip weekends, all starting from Friday, October 2, 2026. The printable 100-day countdown tracker lets a class or family color one box a day toward a goal.
Date calculator add days, weeks, months or years
Adding days is simple counting on the calendar: the start date is day 0 and the next day is day 1. In any date calculator, add days is the most common job, from a 30-day return window to a 90-day trial. Starting on Friday, October 2, 2026:
- 30 days later is Sunday, November 1, 2026.
- 90 days later is Thursday, December 31, 2026.
- 6 weeks (42 days) later is Friday, November 13, 2026.
- 1,000 days later is Thursday, June 28, 2029.
Weeks are simply 7 days each. Months and years work differently, because months have different lengths: adding a month keeps the same day number, so March 15 plus one month is April 15. If that day does not exist in the new month, the calculator uses the last day of the month instead: January 31, 2027 plus one month is February 28, 2027, and February 29, 2028 plus one year is February 28, 2029.
100 days from today
To find 100 days from today, leave the start date as today, type 100 and choose days. From Friday, October 2, 2026, 100 days from today is Sunday, January 10, 2027. Schools celebrate the 100th day of school, fitness and reading challenges often run for 100 days, and many people count down 100 days to a wedding, a trip or a due date. The add days to date calculator finds the exact day, and the printable 100-day tracker above turns any of these into a coloring chart: write the start date, find day 100 with the calculator and color one box each day.
Subtract days from date: counting backwards
To subtract days from date values, type a negative number in the add days to date calculator. From Friday, October 2, 2026, subtracting 30 days gives Wednesday, September 2, 2026. Counting back is useful for working out when something started, such as the first day of a 14-day quarantine or the date a 60-day notice period began, or the last day to post something so that it arrives in time. To find the number of days between two dates instead, use the days between dates calculator.
Business days calculator: weekdays only
Choose weekdays as the unit and the calculator works as a business days calculator, skipping Saturdays and Sundays. From Friday, October 2, 2026, adding 10 weekdays lands on Friday, October 16, 2026, which is 14 calendar days later. Adding 30 weekdays lands on Friday, November 13, 2026.
Public holidays are not skipped, because they differ by country, state and employer. If your deadline excludes holidays, add one extra weekday for each holiday in the period. In the United States, Columbus Day (October 12) and Veterans Day (November 11) fall inside that 30-weekday window, so a deadline that excludes both moves to Tuesday, November 17. The 2026 calendar and 2027 calendar list the federal holidays and their observed dates.
Everyday uses to add days to date
- Deadlines: 30, 60 or 90 days for returns, bills, notices and contracts.
- Pregnancy and pets: due dates are often counted as a number of weeks from a known date; ask your doctor or vet for the exact method they use.
- Medicine and plans: the end date of a 14-day or 21-day course or program.
- School: the 100th day of school, the end of a grading period or the date of a big test.
- Travel: visa and passport rules that count days from your arrival date.
Our calendar follows the Gregorian calendar, including leap years such as 2028, so February 29 is counted correctly. To find which weekday any date falls on, try the day of the week calculator, and for a visual countdown, the countdown calendar maker.
Add days to date: frequently asked questions
What is 100 days from today?
Leave the start date as today, type 100 and choose days. From October 2, 2026, it is Sunday, January 10, 2027.
Does adding weekdays skip holidays?
No, only Saturdays and Sundays. Check your own calendar for public holidays and add a day for each.
Does add days to date count the start date?
No. The start date is day 0, so adding 1 day gives the next day. If you need to include both the start and end dates, add one more day.
How do I subtract days?
Type a minus sign before the number, such as -45.
What happens when I add a month to January 31?
The result uses the last day of the next month, such as February 28, because February 31 does not exist.
How far ahead can the add days to date calculator go?
Up to 100,000 days, weeks, months, years or weekdays in either direction.
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