Date Calculator – Days Between Dates, Add/Subtract Days Online

Calculate the number of days between any two dates, or add/subtract days from a date. Our free date calculator handles business days, weeks, months, and years with precision.

What Is a Date Calculator?

A date calculator performs arithmetic on dates—finding the difference between two dates, or adding/subtracting time periods from a specific date. It eliminates the complexity of varying month lengths, leap years, and calendar quirks.

Calculation Types

How to Use This Tool

Calculate Days Between Dates

1. Enter the start date
2. Enter the end date
3. View the difference in days, weeks, months, and years

Add or Subtract Days

1. Enter a starting date
2. Enter the number of days to add or subtract
3. View the resulting date

Common Use Cases

Business & Legal

• Contract deadlines — Calculate due dates
• Notice periods — Determine resignation end dates
• Statute of limitations — Count legal deadlines
• Probation periods — Track 90-day reviews
• Payment terms — Net 30, Net 60 calculations

Project Management

• Sprint planning — Calculate sprint end dates
• Milestone tracking — Days until deliverables
• Project timelines — Duration calculations
• Vacation planning — Count days off

Personal Life

• Age calculations — Exact age in days
• Anniversary countdown — Days until special dates
• Pregnancy tracking — Due date calculations
• Fitness goals — 30-day challenge tracking

Finance

• Interest calculations — Days in interest period
• Investment holding periods — Capital gains timing
• Bill due dates — Days until payment
• Subscription tracking — Trial period end dates

Business Days vs. Calendar Days

Business Days Calculation

• Excludes Saturdays and Sundays
• Holidays may or may not be included (specify your requirements)

Date Calculation Examples

Frequently Asked Questions

Does it account for leap years?

Yes! February 29 is automatically included in leap years (divisible by 4, except century years not divisible by 400).

Is today included in the count?

This depends on your counting method:

• Inclusive: Both start and end dates count
• Exclusive: Only days between (most common)
• Our tool shows both calculations.

How do I calculate just business days?

Toggle the "Business Days Only" option to exclude Saturdays and Sundays from your calculation.

Can I account for holidays?

Holiday exclusion varies by region and organization. Our business days calculation excludes weekends; you may need to manually adjust for holidays.

What's the maximum date range?

Calculate dates spanning centuries—from ancient history to far-future dates. The tool handles any valid calendar date.

How accurate is this for historical dates?

Modern Gregorian calendar calculations are exact. Pre-1582 dates (before Gregorian adoption) may have minor variances depending on regional calendar adoption.

Handling Tricky Cases

Month-End Calculations

Adding "1 month" to January 31 gives February 28/29, not March 3. Month endings are handled intelligently.

Year Calculations

Adding "1 year" on Feb 29 gives Feb 28 in non-leap years.

Time Zones

Date calculations use calendar dates without time zones. For time-sensitive calculations, consider the Time Calculator.

Pro Tips

1. Double-check endpoints — Know if start/end dates are included
2. Verify business days — Different countries have different workweeks
3. Account for holidays — Manually adjust for public holidays
4. Use for planning — Count backwards from deadlines
5. Save key dates — Note important calculation results

Date Reference

Days in Each Month