Calculate how many years, months and days since a wedding or other date, when your next anniversary falls, or the date of a year, month or day milestone.
Related Calculators
- Days To Go Calculator
- Age In Days Calculator
- Weeks To Go Calculator
- What is 48 Hours From Now? + Calculator
- All Everyday Life and Education Calculators
Anniversary Formula
Choose elapsed time and next anniversary, the date of a numbered annual anniversary, or an elapsed-day milestone. Enter the visible fields; the event date is day zero.
For the elapsed-years formula, the adjustment value is:
- AD = anniversary date
- SD = start date
- Y = number of full calendar years
- A = adjustment for whether the anniversary month and day has occurred yet in the anniversary year
If you enter the start date and number of years, the calculator adds that many calendar years to find the anniversary date.
For a day milestone, enter the event date, as-of date and number of full calendar days. The result shows the milestone date and its distance from the as-of date.
For elapsed time, enter the event date and as-of date. The calculator counts full years under your February 29 convention, then months clamped from the last annual date, then remaining days. The next anniversary is strictly after the as-of date.
Common Anniversary Year Names
Some anniversaries have traditional names. The table below shows common milestone years.
| Years | Common Anniversary Name |
|---|---|
| 1 | First anniversary |
| 5 | Fifth anniversary |
| 10 | Tenth anniversary |
| 25 | Silver anniversary |
| 50 | Golden anniversary |
| 60 | Diamond anniversary |
How Full Years Are Counted
When calculating the number of years between two dates, the calculator counts full years only.
| Start Date | Anniversary Date | Full Years | Reason |
|---|---|---|---|
| 2020-06-15 | 2025-06-15 | 5 | The month and day match. |
| 2020-06-15 | 2025-06-14 | 4 | The anniversary day has not occurred yet in 2025. |
| 2020-06-15 | 2025-07-01 | 5 | The anniversary day has already passed in 2025. |
Example
Example 1: Find an anniversary date
You started on 2016-04-20 and want to find the 10-year anniversary.
Anniversary date = 2026-04-20
Example 2: Find the number of full years
You started on 2018-09-10 and the anniversary date is 2024-09-09.
The month and day, September 9, is before September 10, so subtract 1.
Number of full years = 5
FAQ
Does the calculator count full years or rounded years?
It counts full calendar years. For example, from 2020-05-10 to 2025-05-09 is 4 full years, not 5, because the fifth anniversary has not happened yet.
What happens if the start date is February 29?
Choose February 28 (the default) or March 1 for anniversaries in non-leap years. This is a planning convention, not a statement of legal anniversary rules.
Can the anniversary date be before the start date?
Not when calculating a non-negative number of years. The anniversary date must be on or after the start date if you want the calculator to return the number of elapsed years.
