Learn how to find the exact number of days, weeks, months, or years between any two dates — useful for deadlines, contracts, anniversaries, and planning.
Step-by-Step Guide
Open the Date Difference Calculator
Enter a start date and end date. The tool calculates the difference in years, months, weeks, days, and optionally in hours.
Choose what unit you need
For contracts or leases, days or months matter most. For project deadlines, business days (excluding weekends) are more useful. Check whether the tool offers a business-days mode.
Manual calculation for days
Subtract the earlier date from the later date. Each month has 28–31 days; remember to account for leap years (February has 29 days in leap years).
Calculate months between dates
Count full months between the two dates, then add the remaining days as a fraction if needed. Example: Jan 15 to Apr 20 = 3 months 5 days.
Common use cases
Days until a deadline: enter today and the deadline date. Age in days: enter birthday and today. Contract duration: enter start and end of contract.
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Date Difference Calculator
Frequently Asked Questions
Q: Does the calculator include the end date?
A: Most calculators count up to but not including the end date. For legal or medical purposes, confirm whether both endpoints are included.
Q: How do I count business days?
A: Subtract weekends (Saturday and Sunday) from the total day count. Our tool offers a business-days mode that does this automatically.
Q: What is the difference between elapsed time and remaining time?
A: Elapsed time counts from a past date to today; remaining time counts from today to a future date. The Date Difference Calculator handles both.