Calculate the number of days, weeks, and months between two dates.
Days Between
Add/Subtract Days
Result
-
-
⚙️ How It Works
A date calculator computes the difference between two dates in days, weeks, months, and years. It can also add or subtract a number of days from a date to find a future or past date. The calculation accounts for varying month lengths, leap years, and calendar rules to give precise results.
Days Between = End Date − Start Date (in days) | Future Date = Start Date + N days | Weeks = Days ÷ 7
Editorial Standards
Author
BetterProduct Editorial Team
Reviewed by
Checked against standard math or conversion logic and browser-side calculation behavior.
Updated
March 2026
Best used for
Quick everyday calculations and unit checks.
Languages checked
7 language editions aligned from the same source formulas.
Use Results Responsibly
Check units and formats before you calculate.
Round only at the end if precision matters.
Use official records for deadlines, utility rates, or school policies when applicable.
❓ FAQ
How many days are in each month?
January, March, May, July, August, October, December have 31 days. April, June, September, November have 30 days. February has 28 days (29 in leap years). A mnemonic: knuckle months have 31 days.
How do I calculate the number of business days between two dates?
Count the total days between the dates, subtract weekends (multiply full weeks by 2, then check remaining days), and subtract any public holidays that fall in the range. Many online tools automate this.
What is the Unix timestamp?
A Unix timestamp is the number of seconds elapsed since January 1, 1970 (UTC). It's widely used in computing to represent dates and times as a single integer. The year 2038 problem occurs when 32-bit systems overflow this counter.
How do different calendars compare?
The Gregorian calendar (used internationally) has 365.2425 days/year. The Julian calendar has 365.25 days/year (slightly off, causing a 13-day difference today). The Islamic calendar is lunar (354 days/year), and the Hebrew calendar is lunisolar.