Need to know exactly how many days separate two dates? Whether you're planning a project deadline, counting days until a vacation, tracking a pregnancy, or calculating the duration of a lease agreement, our free days between dates calculator gives you an instant, precise answer. Simply pick a start date and an end date and the tool does the rest — no manual counting required.
The calculator shows the total number of calendar days, a human-readable breakdown into years, months, weeks, and days, plus total hours, minutes, and seconds. Toggle "Include end date" when you need to count both boundary dates (for instance, an event that starts Monday and ends Friday is 5 days if you include both days). Toggle "Business days only" to strip out weekends and US federal holidays automatically.
Calculating the number of days between two dates by hand is surprisingly error-prone. You have to account for months with 28, 29, 30, or 31 days, leap years that add an extra day every four years (with exceptions for century years), and the fact that not every "month" means the same duration. A span from January 15 to March 15 crosses one 31-day month and one 28-or-29-day month — easy to miscount.
The simplest manual method is to convert both dates to their Julian day number (the count of days since a fixed epoch) and subtract. That's essentially what computers do: JavaScript's Date object stores dates as milliseconds since January 1, 1970, so subtracting two dates and dividing by 86,400,000 gives exact day counts, including leap years.
For a quick mental estimate, remember that each month averages about 30.44 days and a year averages 365.25 days. But for precise results — especially for legal, financial, or medical calculations — use a tool like this one.
Calendar days include every day on the calendar — weekdays, weekends, and holidays alike. When a contract says "within 30 days," it almost always means calendar days. Business days (also called working days or weekdays) exclude Saturdays and Sundays. In the United States, business-day calculations often also exclude the 10 federal holidays: New Year's Day, Martin Luther King Jr. Day, Presidents' Day, Memorial Day, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving, and Christmas Day.
This distinction matters for shipping estimates, legal deadlines, payroll calculations, and project timelines. Our calculator makes it easy: flip the "Business days only" toggle and any weekends and US federal holidays in the range are automatically removed from the count. The holidays that fall within your date range are displayed below the results so you can verify them.
| Question | Answer |
|---|---|
| How many days in a year? | 365 (366 in a leap year) |
| How many weeks in a year? | 52 weeks and 1 day (52 weeks and 2 days in a leap year) |
| How many business days in a year? | About 251–252 (varies by year and holidays) |
| How many days in a month? | 28–31, depending on the month |
| How many days until Christmas? | See our Christmas countdown |
| How many days until New Year? | See our New Year countdown |
| How old am I in days? | Use our Age Calculator |
Looking for more date tools? Try our Date Calculator for add/subtract operations, the Age Calculator for exact age from a birthdate, or browse countdown timers for any duration.