Date Calculator
Calculate days between dates, add or subtract time, and find day of the week.
Date Difference
Add / Subtract from Date
Day of Week
Frequently Asked Questions
How do I calculate days between two dates?▼
Subtract the start date from the end date to get the difference in milliseconds, then divide by (1000 × 60 × 60 × 24) to convert to days. This calculator does it instantly — just pick two dates.
How do months work when adding to a date?▼
Adding months adjusts the month component. January 31 + 1 month = February 28/29 (last day of February). Calendars handle the variable month length automatically. This calculator uses standard JavaScript date arithmetic.
What is a business day calculation?▼
Business days exclude weekends (Saturday and Sunday) and sometimes holidays. To count business days between dates, subtract the number of weekend days and applicable holidays from the total calendar day count.
How do I find what day of the week a date was?▼
Use the Day of Week section above — just enter any date and it instantly shows the day name, ISO week number, and whether it's a weekday or weekend.