How the days are counted
By default this counts the days between two dates, which means the start date is excluded and the end date is included. From 1 January to 8 January is seven days.
Tick "include the end date" and both endpoints count, giving eight. This is the right mode for things measured in occupied units — hotel nights, days of leave, or the length of an event.
Business days
Business days exclude Saturdays and Sundays. Note that this calculator does not exclude public holidays, which vary by country, state and even industry — subtract those yourself for contractual deadlines.
A worked example
Common uses
| Situation | Mode | Note |
|---|---|---|
| Notice periods | Between | Contracts usually count from the day after notice is given |
| Hotel nights | Between | Check-in to check-out is nights, not days |
| Annual leave | Inclusive | Both the first and last day off are used |
| Project deadlines | Business days | Remember to subtract public holidays |
| Age or anniversaries | Years/months/days | Calendar-aware, not just days ÷ 365 |
| Payment terms | Between | "Net 30" means 30 days from the invoice date |
For age specifically, the age calculator handles birthdays and leap years properly. To add or subtract a period from a date, use the date calculator.
Frequently asked questions
How do I count the days between two dates?
Subtract the earlier date from the later one. Whether you include the end date depends on what you are measuring — hotel nights exclude it, leave days include it.
This calculator shows both figures so you do not have to guess.
How many business days are between two dates?
Count the total days, then subtract Saturdays and Sundays. The calculator does this automatically.
Public holidays are not excluded, since they vary by country and region. Subtract them separately for contractual deadlines.
Does this account for leap years?
Yes. The calculation works on actual calendar dates, so 29 February is counted when it falls within the range.
This is why dividing by 365 gives the wrong answer over multi-year spans.
Why does the years-months-days figure not match days ÷ 365?
Because months have different lengths. The years-months-days breakdown walks the calendar properly, the same way age is calculated.
Days ÷ 365 gives an average, not a calendar-accurate result.