Date Calculator
Find the date a number of days, weeks, months or years from any day, or count business days only. Then compare two dates in years, months and days.
- Add & subtract
- Business days
- Weekday shown
- Date difference
Add or subtract from a date
Defaults to today.
Choose a start date and an amount of time.
Months are added first, then weeks and days. Adding a month to 31 January gives the last day of February.
Time between two dates
Defaults to today.
Pick an end date to count the days.
The day count excludes the start date, the way most people count “days until”. Tick “Include the end date” to count both ends, for example for a hotel stay or a leave request.
What is a date calculator?
A date calculator works out a future or past date from a starting date and an amount of time, such as “90 days from today” or “6 months before 1 March”. It handles month lengths and leap years for you. This calculator can also skip weekends and public holidays to count business days, and compares two dates as years, months and days plus the total number of days.
How to use Date Calculator
- Choose a start date. It is today unless you change it.
- Pick Add or Subtract and enter years, months, weeks and days in any combination.
- Tick “Count business days only” to skip weekends and US or UK public holidays.
- Read the resulting date and weekday. Scroll to the second calculator to compare two dates.
How date arithmetic works
- Months and years are added first, then weeks and days, which matches how people count “3 months and 10 days”.
- When the target month is shorter, the date moves to that month’s last day: 31 January + 1 month = 28 February (29 in leap years).
- Business days skip Saturdays, Sundays and the selected public holidays. Holidays that fall on a weekend use their observed weekday.
- Dates are calculated as calendar days, so daylight-saving changes never shift the result.
Why use this date calculator
- Months done rightAdding a month to 31 January gives the last day of February, and leap years are handled automatically.
- Business days built inSkip weekends plus US federal or UK bank holidays for deadlines and delivery dates.
- Two calculators in oneAdd or subtract time, then compare any two dates on the same page.
- Private by defaultEverything is calculated in your browser. Dates, times and pay rates are never sent to a server.
Common uses
- Deadlines. Find the date 30 days after an invoice or 10 business days after a request.
- Pregnancy and health. Count weeks from a date, such as 40 weeks from a start date.
- Contracts and notice periods. Work out when a 3-month notice period ends.
- Travel and events. Plan the date that is 100 days from today.
More time and date tools: days between dates, business days, age calculator, time calculator, hours calculator, time card, military time, time zones.
Example: a 90-day return window
You bought something on 12 October 2026 and the return window is 90 days. Enter 12 October, choose Add and type 90 in Days: the last day to return it is Sunday, 10 January 2027. If the shop counts business days, tick the box and choose US holidays for a later date that skips weekends, Thanksgiving, Christmas and New Year’s Day.
What to expect from the result
Public holidays cover US federal holidays and bank holidays in England and Wales. State, regional and company holidays can be added manually on the business days calculator. Historic dates use today’s Gregorian calendar.
Date Calculator questions
How do I add days to a date?
Enter the start date, choose Add, type the number of days and read the result. For example, 30 days after 1 September 2026 is 1 October 2026.
What date is 90 days from today?
Leave the start date as today, choose Add and enter 90 days. The calculator shows the date and its weekday instantly.
How are months added when the day doesn’t exist?
The result moves to the last day of the shorter month. 31 January plus one month is 28 February, or 29 February in a leap year.
Can I add business days only?
Yes. Tick “Count business days only” and choose US federal holidays, UK bank holidays or none. Weekends are always skipped.
Can I find the number of days between two dates?
Yes. Use the second calculator on this page, or the dedicated days between dates calculator, for years, months, weeks and total days.