Date Calculator
Find days between dates, or calculate a new date by adding or subtracting days
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Frequently Asked Questions
How do I calculate the number of days between two dates?
Subtract the earlier date from the later date in milliseconds, then divide by 86,400,000 (ms per day). Our calculator handles leap years, different month lengths, and daylight saving time automatically.
What is the difference between business days and calendar days?
Calendar days count all 7 days per week. Business days count only weekdays (Monday–Friday), excluding weekends and sometimes public holidays. Shipping estimates and legal deadlines often use business days.
How do I add or subtract days from a date?
Add or subtract the number of days in milliseconds (1 day = 86,400,000 ms). The result will cross month and year boundaries automatically. Use our calculator to instantly find the date 30, 60, or 90 days from any date.
How many days until a specific date?
Subtract today's date from the target date. Our calculator does this automatically when you enter today as date 1 and your target as date 2. Use the Age Calculator for birthdays and the Days Until calculator for countdowns.
Why do date calculations get complicated near month ends?
Months have 28–31 days, and leap years affect February. Adding "one month" to January 31 is ambiguous — does it become February 28 or March 3? Our calculator adds exact calendar days to avoid ambiguity.