Date Difference Calculator
Days, weeks, months, and years between two dates.
Enter any two dates to instantly see the gap in days, weeks, months, years, and business days. Works entirely in your browser with no data sent anywhere.
Calendar vs Business Days
Calendar days vs business days
Calendar days count every single day between two dates — Saturdays, Sundays, and public holidays included. This is the right measure for countdowns (days until a birthday, an event, or a deadline), duration of a trip, or project elapsed time. Business days count only Monday through Friday, skipping weekends, and are used in legal contracts, invoice payment terms, SLA agreements, and HR policies. This calculator shows both simultaneously.
Important: public holidays are not subtracted
Business day counts here skip only Saturdays and Sundays. Public holidays (Christmas, national days, bank holidays) vary by country, state, and year — there is no universal list. If your calculation is for a legal contract or a payment term that explicitly excludes public holidays, subtract the relevant holidays manually from the business day total shown. For personal use and most project management, the weekend-only business day count is sufficient.
Calendar days = |End date − Start date| in daysBusiness days = Calendar days, excluding Sat & Sun Real-world scenarios where this matters
Invoice payment terms are stated as "net 30" or "net 60" — almost always calendar days, not business days, unless the contract specifies otherwise. Visa and passport applications often quote processing times in business days. Loan approval timelines, insurance claim windows, and warranty periods are typically calendar days. Court filing deadlines and statutory notice periods in employment law are business days with public holidays excluded. Employment contracts state notice periods in calendar weeks or months. Event planning — booking venues, sending invitations, ordering catering — works in calendar days. Understanding which measure applies to your situation prevents missed deadlines.
Negative results and reverse calculations
If the end date is before the start date, the calculator returns a negative result — useful for calculating how many days have passed since a missed deadline, how long ago an event occurred, or how overdue a payment is. Enter a past date as the "end" and today as the "start" to see the overdue count in both calendar and business days.
Frequently Asked Questions
Does the calculator count the start date or end date?
It counts the days between the two dates exclusively — the start date itself is not counted. For example, from Jan 1 to Jan 3 gives 2 days.
Does it account for public holidays in business days?
No. The business days count skips only Saturdays and Sundays. Public holidays vary by country, state, and year, so you'll need to subtract those manually if required.
What happens if I enter the end date before the start date?
The calculator still works and shows a negative result, indicating the end date is earlier than the start date. This is useful for counting days since a past deadline.
How accurate are the months and years results?
Months are approximated using 30.4375 days per month and years using 365.25 days per year (accounting for leap years). For an exact month or year count, the result may differ by a day depending on the specific months involved.
Can I use this to calculate age?
Yes. Enter your birth date as the start date and today's date as the end date. The years result gives your age in decimal form, and total days gives the exact count.
What is the formula for the Date Difference Calculator?
Difference = End date − Start date. The total days is the absolute difference divided by 86,400,000 milliseconds per day. Business days are counted by iterating each day and checking whether it falls on Monday through Friday.