Days Between Dates
Calculate the duration between two dates
Why Count Days Between Dates?
Date duration calculations are more useful than they may seem at first glance. Knowing the exact number of days between two dates helps with: project planning (calculating deadlines and timelines), financial calculations (interest accrual periods, loan terms, lease durations), legal deadlines (filing periods, statute of limitations, response windows), personal milestones (days until a birthday, anniversary, or event), and countdown timers for travel, weddings, and events.
Calendar Days vs Business Days
This calculator counts calendar days — every day of the week including weekends and public holidays. For many professional purposes, you may need business days (weekdays only, excluding Saturday and Sunday). To estimate business days, divide calendar days by 7, multiply by 5, and add the remaining weekdays.
Example: 30 calendar days ≈ 21 business days. Most legal and financial deadlines specify "business days" or "calendar days" explicitly — always confirm which applies to your situation.
How Leap Years Are Handled
A leap year occurs every 4 years (year divisible by 4), except for years divisible by 100 unless also divisible by 400 (so 2000 was a leap year, but 1900 was not). This gives February 29 days instead of 28. When calculating date spans that cross a leap year's February, the calculator automatically accounts for the extra day — so the difference between January 1, 2024 and March 1, 2024 is 60 days (not 59), because 2024 is a leap year.
Frequently Asked Questions
Is the end date included in the count? This calculator counts the absolute difference between dates — for inclusive ranges (where you want to count both the start and end date), add 1 to the result.
Can I calculate days across multiple years? Yes — the calculator handles date differences of any length, including multi-year spans. It accounts for leap years in all multi-year calculations.
How are months calculated? The "months" figure shown is an approximation using 30.44 days/month (the average month length in a year). For exact month counts, note that months have 28–31 days.
What is the maximum date range supported? This calculator supports any dates within the JavaScript Date object range — roughly year 1 through year 275,760. Practically, it works for any historical or future date you would realistically need.