Couple Days Calculator
Last updated: 2026-06-25
With the day-one-inclusive method that counts the day you met as day 1, couple 100 days is 99 days after the start date and 1000 days is 999 days after.
Pick the start date and instantly see how many days you have been together plus the dates for 100, 200, 300, 500, and 1000 days and your first year.
Enter start date
Days together
Day 0
| Milestone | Date | D-day |
|---|
Dates are calculated by the difference in days excluding time, and may differ by one day depending on whether the first day is included. Results are for fun and reference.
How to use
- Pick the start date — Choose the day you first met or started dating from the calendar.
- Calculate — Press Calculate to see how many days you have been together and your key anniversary dates.
- Check the anniversaries — Review the dates and remaining days for 100, 200, 300, 500, and 1000 days plus your first year in a table.
How couple 100 days and 1000 days are calculated
By the most common day-one-inclusive method, the day you started dating counts as day 1. With this method the start date itself is day 1, so the Nth-day anniversary falls (N − 1) days after the start date. That makes 100 days = start + 99 days, 200 days = + 199 days, and 1000 days = + 999 days.
By contrast, the day-one-exclusive method treats the day after the start as day 1, so the Nth day is start + N days. The two methods differ by a day, so it is a good idea to agree with your partner on which rule you use.
| Milestone | From start date | Note |
|---|---|---|
| 100 days | +99 days | The most celebrated first milestone |
| 200 days | +199 days | |
| 300 days | +299 days | |
| 500 days | +499 days | Halfway to 1000 |
| 1 year (365 days) | +364 days | 1–2 days off from the same calendar date |
| 1000 days | +999 days | About 2 years 9 months |
Note that the "first anniversary" counted in days is day 365 (start + 364 days when the first day is included), but many people celebrate the same calendar month and day (for example last year's March 5 → this year's March 5) as the first anniversary. A leap year can cause a one-day difference between the two. To count down to a specific anniversary, use the Anniversary D-day Calculator, and for wedding anniversaries use the Wedding Anniversary Calculator.
Frequently asked questions (FAQ)
How are couple 100 days counted?
By the common day-one-inclusive method, the day you first met counts as day 1. So day 100 falls 99 days after the start date, and adding 99 days to that first day gives the 100 day anniversary. This calculator uses the day-one-inclusive method by default.
How many days after the start is 1000 days?
With the day-one-inclusive method, day 1000 is 999 days after the start date. For example, if you met on January 1, that day is day 1 and adding 999 days gives the 1000 day anniversary.
How are days together calculated?
Days together count the start date as day 1 through today. In other words it is (today minus start date) plus 1, so on the start date itself it is day 1. Only the date is used; time of day is ignored.
When should I prepare a 100 day gift?
Use the 100 day date and remaining days shown here and prepare one or two weeks ahead. Popular restaurants and cakes book up fast, so reserving around D-7 to D-14 is a good idea. The dates are for reference, so follow your own plan if you have one.
Related calculators & guides
Anniversary D-day Calculator
Count the days until or since a specific date.
Wedding Anniversary Calculator
Check your anniversary year and names like silver and golden.
Wedding Anniversary Names & Meanings
A guide to anniversary names and their origins by year.
Anniversary Calculator Home
Couple, D-day, and wedding calculators in one place.
Last updated: 2026-06-25