How many days are between two dates?
The primary Days between result is the elapsed interval: Start is day zero, so the same date to itself is 0 days. Inclusive date count adds one when you need to count both calendar dates.
Calendar arithmetic
Date Calculator
Calculate days between two dates, or add and subtract years, months, weeks, and days from a calendar date. Results use deterministic Gregorian civil-date arithmetic.
Days between dates
Start is day zero. The primary result is elapsed calendar days; inclusive counting is shown separately.
Start calendar
End calendar
Add or subtract calendar units
Years and months move the calendar first. Weeks and days are then applied as exact calendar days.
Base calendar
Gregorian leap years
The calculator uses the Gregorian leap-year rule: years divisible by 4 are leap years, except century years unless they are divisible by 400. That makes 1900 a common year and 2000 a leap year.
Months and years are calendar units
Months and years do not have a fixed number of days. Adding one month to January 31 is constrained to the last valid day of February: January 31, 2019 + 1 month = February 28, 2019; in 2020 it becomes February 29.
Leap-day example
February 28, 2024 to March 1, 2024 is 2 days because February 29 exists. Adding 1 year to February 29, 2024 produces February 28, 2025.
How calendar difference works
The calendar difference is expressed as whole years and months from the Start date, constrained at month ends, plus the remaining exact days. This is different from pretending every month has 30 days.
Business days and holidays
This app counts ordinary Gregorian calendar dates. It does not remove weekends or holidays and does not apply regional business-day rules.
Choose the right Time & Date app
Use Time Duration Calculator when time-of-day matters. Use Time Calculator for duration quantities and clock shifts. Age/date-of-birth calculations belong to a separate age-specific app.
Learn the method
Read How to Calculate Days Between Dates for ordinal-day arithmetic, inclusive counting, leap years, calendar decomposition, month-end behavior, and worked examples.
Privacy and page memory
Your date inputs remain in page memory only. The app does not store calculator work in localStorage, sessionStorage, IndexedDB, cookies, or a backend. Share App uses only the canonical Date Calculator URL, not your entered dates.