Date Difference Calculator
Calculate the gap between any two dates
What is a date difference?
A date difference is the amount of time that separates two calendar dates. Depending on the context, this can be expressed in total days, weeks, months, or years — each unit useful for different purposes.
Unlike simple subtraction, precise date differences must account for varying month lengths (28 to 31 days) and leap years, which add one extra day every four years (with century exceptions).
Common uses
- Project management — how many days until a deadline, or how long a project took.
- Countdowns — days until a wedding, holiday, exam, or event.
- Finance and loans — interest accrual calculations based on exact days between dates.
- Legal deadlines — court filings, contract notice periods, statute of limitations.
- HR and payroll — notice periods, probation durations, leave calculations.
- Medical — gestational age, medication intervals, follow-up scheduling.
Examples
| Start date | End date | Difference |
|---|---|---|
| Jan 1, 2025 | Dec 31, 2025 | 364 days (not a leap year) |
| Jan 1, 2024 | Dec 31, 2024 | 365 days (2024 is a leap year) |
| Feb 1, 2025 | Mar 1, 2025 | 28 days |
| Sep 1, 2025 | Sep 1, 2026 | 365 days (1 year) |
What are business days?
Business days (also called working days) are weekdays — Monday through Friday — excluding weekends and public holidays. The number of business days between two dates is commonly used in contracts, legal notices, and shipping estimates.
Our calculator estimates business days by counting weekdays between the two dates. Note that public holidays vary by country and are not automatically excluded — subtract them manually based on your region.
Frequently asked questions
A common year has 365 days. A leap year has 366 days — leap years occur in years divisible by 4, except century years, which must be divisible by 400 (e.g. 2000 was a leap year, but 1900 was not).
By default, the count is exclusive of the start date and inclusive of the end date (i.e. the difference between Jan 1 and Jan 2 is 1 day). This matches the most common convention in date math.
Leave the start date as today (it's pre-filled) and enter your target date in the end date field. The result will show exactly how many days from now until that date.
Yes. Set the end date before the start date, or swap the dates — the calculator will return the absolute difference regardless of order.