Example 1
- Start: February 28, 2024
- Unit: calendar days
- Amount: 1
February 29, 2024
In a leap year, plus 1 from February 28 lands on February 29.
Date calculator
Choose a start date, a direction, and a unit: calendar days, weeks, months, years, or Monday–Friday business days. Use Today for today’s date. February 28, 2024, plus 1 day lands on February 29. Friday plus 1 business day lands on Monday.
If you already know both dates and want the gap between them, use difference between dates. If business days should also exclude public holidays, open the business-days calculator. A pregnancy due date — usually about 280 days from the last menstrual period — is on the due date page.
Result
Choose a start date and an amount of calendar days to add. The result appears here.
How the result is calculated
StartFeb 28, 2024
+1 daycalendar
ResultFeb 29, 2024
From Friday, three calendar days end on Monday. Three business days end on Wednesday, because Saturday and Sunday are not counted.
The calculator moves a date by the number of units you choose. Days and weeks are multiples of calendar days. For months and years it moves the month or year on the calendar; if the target month is shorter, the day is shortened to that month’s last day — for example January 31 plus 1 month lands on February 28 or 29.
Business days on this page are Monday–Friday. Saturday and Sunday are skipped. Public holidays are not removed here — use the separate business-days calculator when you need a holiday list.
Use Add or Subtract instead of a minus sign in the amount field. With zero units, the result is the same start date. A fraction is truncated to a whole number.
The result shows the date, weekday, calendar span, and a short timeline from start to result. Currency and US/metric switches do not apply here.
How to use it
- Choose a start date, or click Today.
- Set the direction: Add or Subtract.
- Choose a unit and enter 0 or a larger number, for example 14.
- Click Calculate. Read the date, weekday, and timeline.
- For business days, check whether the contract also excludes holidays — then open the business-days calculator.
Formula
days / weeks: new date = start ± N × (1 or 7) calendar days
months / years: move the month or year; day = min(start day, last day of the target month)
business days: step one calendar day at a time and count only Monday–Friday until N is reached
Common deadlines: calendar or business days
The same number in a contract can mean calendar days or business days. The table shows how the end date changes from Friday, January 5, 2024 — worth checking before you copy a deadline from a contract into your calendar.
| Situation | Count | Mode | Result from Jan 5, 2024 |
|---|---|---|---|
| 14-day return | 14 | calendar | January 19, 2024 |
| 30-day notice | 30 | calendar | February 4, 2024 |
| 10 business days | 10 | business | January 19, 2024 |
| 10 calendar days | 10 | calendar | January 15, 2024 |
| 3 months | 3 | months | April 5, 2024 |
From a Friday, 10 calendar days and 10 business days are four calendar days apart, because weekends push the business-day deadline further out. For returns and notice periods, compare both end dates side by side so the effect of the wording is clear.
Calendar and business days
The new date depends on the unit. Calendar days count every day. Business days on this page are Monday–Friday.
- Calendar day
- Every day on the calendar, including weekends. January 5, 2024 plus 3 lands on January 8.
- Business day
- Monday–Friday. January 5, 2024 plus 3 business days lands on January 10. Holidays are not removed on this page.
- Month
- The calculator moves the month on the calendar. If the target month is shorter, the day is shortened to its last day: January 31 plus 1 month is February 28 or 29.
Examples
Example 2
- Start: January 5, 2024 (Friday)
- Unit: calendar days
- Amount: 3
January 8, 2024
Weekends stay in the count, so the result falls on Monday.
Example 3
- Start: January 5, 2024 (Friday)
- Unit: business days
- Amount: 3
January 10, 2024
Saturday and Sunday are skipped, so the result falls on Wednesday.
Example 4
- Start: January 31, 2024
- Unit: months
- Amount: 1
February 29, 2024
February 2024 has 29 days, so the 31st is shortened to the 29th.
Example 5
- Start: March 1, 2024
- Direction: subtract
- Amount: 1 day
February 29, 2024
Choose Subtract instead of typing a minus in Amount.
Example 6
- Start: January 1, 2024
- Unit: years
- Amount: 1
January 1, 2025
Exactly one year later, same month and day.
Example 7
- Start: January 5, 2024
- Unit: calendar days
- Amount: 14
January 19, 2024
Fourteen calendar days for a return, starting from a Friday.
Example 8
- Start: January 5, 2024
- Unit: weeks
- Amount: 2
January 19, 2024
Two weeks is 14 calendar days, so the result falls on the same weekday.
Suggested uses
- Set a return deadline or a notice end date when the contract says “14 days from the date,” not “by May 3.”
- Check whether plus 1 from February 28 lands on February 29 before you put a leap-year date into an amendment.
Common questions
Where does February 28, 2024 plus 1 day land?
On February 29, 2024, because that year is a leap year. In 2023 the same plus 1 lands on March 1, because February 29 does not exist then.
What is the difference between a calendar day and a business day?
A calendar day counts every day, including Saturday and Sunday. A business day on this page is Monday–Friday. Public holidays are not removed here — use the business-days page for a holiday list.
What date do you get from Friday plus 1 business day?
Monday. Saturday and Sunday are skipped, so one business day from Friday lands on Monday.
How are months and years counted?
The calculator moves the month or year on the calendar and keeps the day of month when that day exists. January 31 plus 1 month lands on February 28 or 29, because February is shorter.
Are negative days allowed?
Instead of a minus in the number, choose Subtract. March 1, 2024 minus 1 day returns to February 29, 2024.
What happens with the fraction 3.7?
The fraction is truncated to a whole number: 3.7 becomes 3.
Does plus 1 calendar day from Friday skip Saturday?
No. In calendar-day mode the result falls on Saturday. Saturday is skipped only in business-day mode.
Where do I count the gap when I already know both dates?
On the date-difference page. Here you know the start date and the unit count, and you want the date after the shift.
Is a 14-day return always 14 business days?
No. A typical consumer return period is 14 calendar days. Business days give a different result — compare both modes in the deadlines table on this page.
Is a due date the same as plus 280?
No. A due date is calculated from the last menstrual period on a separate page. Here you enter whatever unit count you need.
Knowledge sources
Date shifts follow the Gregorian calendar. What counts is the calendar day, not the time zone or the hour on a clock.
Page updated October 7, 2026.