📆 Date Difference Calculator

Find the difference between two dates in years, months, days, and also total days, weeks, and months. Useful for project planning, age tracking, or event countdowns. Batch CSV mode supported.

Single Date Difference





Result: -

Batch Mode (CSV Upload)

Upload CSV lines like:

start,end
2020-01-01,2025-09-23
2025-01-01,2025-12-31

Understanding Date Differences

Calculating the difference between two dates may seem simple — subtract one from the other — but in reality calendars bring complexity: leap years, varying month lengths, and historical calendar reforms. A good calculator should handle these nuances correctly.

1. Years, Months, Days

The most intuitive expression of date difference is in years, months, and days. For example, from 2000-01-01 to 2025-09-23 is 25 years, 8 months, 22 days.

2. Total Days and Weeks

For contracts, countdowns, or analytics, total days or weeks is more useful. Our calculator outputs both.

3. Months as 30 Days?

Some financial contexts approximate months as 30 days, but ISO age calculation uses real calendar months and days.

4. Leap Years

Leap years (every 4 years, except centuries not divisible by 400) add complexity. February 29 must be considered in accurate date math.

5. Applications

  • Project Management: Calculate durations in weeks or months.
  • HR & Payroll: Service lengths, leave entitlements.
  • Personal: Age milestones, countdowns.

6. Worked Examples

Example 1: Start: 2020-01-01, End: 2025-09-23 → 5 years, 8 months, 22 days → total ~2092 days.

Example 2: Start: 2025-01-01, End: 2025-12-31 → 0 years, 11 months, 30 days → 364 days.

7. FAQs

Does it include both start and end dates?

Our calculator measures exclusive difference (days between). Add 1 if you want inclusive range.

Can I use past and future dates?

Yes, negative results just mean the end is before the start.

Does it handle leap-year birthdays?

Yes, Feb 29 is accounted for when present.

8. Conclusion

A reliable date difference calculator ensures precision across legal, financial, and personal planning contexts.