Three calculators in one
- Days between dates: the number of days between two dates, plus weeks, months and hours. Turn on Include the start date when both the first and last day should count, as with trip or event days.
- Add or subtract days: the date that falls N days after or before any date, with the weekday.
- Milestones: from a start date (a relationship, a baby's birth, a habit streak), every milestone from 100 to 10,000 days plus 1st–10th anniversaries, with the next one highlighted.
Counting the first day
Some traditions count the first day as day 1. In Korea, for example, a couple's 100th day falls 99 days after they started dating. Others, like most contracts, start counting the day after. The milestones tab lets you choose; anniversaries always land on the same calendar date each year.
Frequently asked questions
Does it account for leap years?
Yes. Every result uses the real calendar, including February 29.
When should I include the start date?
When both the first and last days count. From the 3rd to the 5th is 2 days without it and 3 days with it.
How are anniversaries calculated?
On the same calendar date each year. A February 29 start date shows March 1 in non-leap years.