Date Calculator
Count the days, weeks, and months between two dates, or add and subtract time from a date to find the result.
Learn how it works: How to Calculate the Days Between Two DatesPick a start and end date to see the difference.
How to use the date calculator
The tool has two modes. Pick "Difference between dates" to measure the gap between two days, or "Add or subtract" to move forward or backward from a starting date by a set amount of time.
In difference mode, set a start and an end date and the result updates straight away, showing the span in total days, in weeks, and as a years, months, and days breakdown. In add or subtract mode, choose a date, pick a direction, type an amount, and select the unit to see the resulting date spelled out in full.
Counting the days between two dates
The day count is inclusive of neither endpoint twice: it is the plain distance from one date to the other, so the same date for start and end is zero days apart, and consecutive days are one day apart. The order you enter the dates does not matter, since the tool always reports a span that is zero or greater.
The weeks line divides that day total by seven and shows any leftover days, which is handy when you are scheduling something a fixed number of weeks out. The years, months, and days breakdown follows the calendar rather than fixed-length months, borrowing the real length of each month so the figure matches how people actually count.
Calendar days, not business days
Every count here is in calendar days. Weekends and public holidays are treated like any other day, so a span that includes a weekend still counts those two days. If you need working days for a project deadline or a contract term, subtract the weekends and holidays yourself, since those vary by country and by company.
This keeps the result predictable and the same for everyone, which is the right default for birthdays, anniversaries, due dates, and any plain countdown where every day counts equally.
How adding months and years works
Adding days or weeks simply walks along the calendar. Adding months and years is where dates get interesting, because not every month has the same number of days. Add one month to January 31 and there is no February 31 to land on.
The tool handles this by clamping to the last valid day of the target month, so January 31 plus one month gives February 28, or February 29 in a leap year. This matches the EDATE behavior most spreadsheets use, which keeps results consistent with the math you may already do in a calendar app or a worksheet.
Frequently asked questions
- How do I count the number of days between two dates?
- Switch to difference mode, then set a start date and an end date. The tool shows the gap in total days, in weeks with any leftover days, and as a years, months, and days breakdown. The order of the two dates does not change the result.
- Does the calculator count business days or calendar days?
- It counts calendar days, so weekends and holidays are included like any other day. Working-day counts depend on the country and the company calendar, so you would need to subtract weekends and holidays yourself.
- What happens when I add a month to the end of a month?
- The result clamps to the last valid day of the target month. Adding one month to January 31 gives February 28, or February 29 in a leap year, since those months have no 31st. This matches the EDATE rule used by most spreadsheets.
- Can I subtract time from a date instead of adding it?
- Yes. In add or subtract mode, set the direction to subtract, then enter the amount and unit. The tool moves backward from your start date and shows the earlier calendar date.
- Are leap years taken into account?
- Yes. The day counts and the month breakdown use real month lengths, including February 29 in leap years, so spans that cross a leap day stay accurate.