Days Between Two Dates
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About this calculator
Enter two dates to find out exactly how many days are between them. The result is always a positive number regardless of date order. This is the most commonly used date difference calculation.
How it works
The calculator normalizes both dates to midnight, computes the absolute difference in milliseconds, and divides by 86,400,000 (the number of milliseconds in one day). By normalizing to midnight, the result is always a clean whole number of days. This avoids timezone and daylight saving time complications that can cause off-by-one errors.
When to use this calculator
Count remaining days until a deadline, vacation, or event. Calculate the length of a trip, rental period, or contract term. Determine how many days are left in a medication course. Track streaks and habits by counting consecutive days. Real estate professionals calculate days-on-market for property listings. Insurance adjusters compute elapsed days for claim processing timelines.
Examples
From January 1, 2025 to March 1, 2025 is 59 days. In a leap year the same span is 60 days, because February gains a 29th day.
A 30-day return window that starts on the purchase date ends on day 30 — count the purchase date as day 0.
Common spans in days
How long familiar date ranges are when measured in days:
| Date range | Days |
|---|---|
| One week | 7 |
| One month (avg) | 30.4400 |
| One year | 365.250 |
| One decade | 3,652.5 |
Frequently asked questions
Are both the start and end dates counted?
The calculator returns the number of days between the two dates. To include both endpoints (an inclusive count), add 1 to the result.
Does it handle leap years?
Yes. Any February 29 inside the range is counted, so a span that crosses a leap day gains one extra day.
Why normalize to midnight?
Normalizing both dates to midnight avoids daylight-saving and timezone off-by-one errors, giving a clean whole-day count.