Last updated: March 2026
How to Count Days Between Two Dates
Counting days between dates manually is surprisingly error-prone. Different month lengths, leap years, and the question of whether to include both endpoints make it easy to be off by one or more. This calculator removes all the guesswork and gives you an instant, accurate answer.
Enter your two dates and get results in multiple useful formats simultaneously. The total calendar day count is most useful for deadlines and countdowns. The business day count excludes weekends, which matters for project timelines, shipping estimates, and legal deadlines that reference "working days."
The year/month/day breakdown makes it easy to communicate durations in human-friendly terms. Saying "2 years, 3 months, and 15 days" is much more intuitive than "836 days." Both are correct; which you use depends on context.
Common use cases include tracking time until a deadline, days since an event, pregnancy duration, contract periods, insurance claim windows, or figuring out exactly how many working days a project will take. The holiday awareness feature shows which US federal holidays fall in your date range — critical for accurate business day planning.
The "Include end date" toggle matters more than you might think. January 1 to January 3 is either 2 or 3 days depending on whether you count both endpoints. Hotel stays, rental periods, and event durations typically include both dates. Elapsed time calculations typically exclude the end date.
Need to know what date falls a certain number of days from now? The Add or Subtract Days section handles that too. Enter a starting date and a number of days (or weeks, months, years) to add or subtract, and get the resulting date instantly.
Frequently Asked Questions
How do I count days between two dates?
Enter your start and end dates above. The calculator instantly shows total calendar days, business days, weekends, weeks, months, and a full year/month/day breakdown. It correctly handles leap years, varying month lengths, and year boundaries.
What are business days vs calendar days?
Calendar days include every day — weekdays, weekends, and holidays. Business days count only Monday through Friday, excluding weekends. Our calculator shows both counts side by side so you can use whichever is relevant for your situation.
Should I include the end date in my count?
It depends on context. For hotel stays (check-in to check-out), include the end date. For age or elapsed time calculations, typically exclude it. Use the 'Include end date' toggle to see both counts. The difference is always exactly one day.
How many days are in a year?
A regular year has 365 days. A leap year has 366 days. Leap years occur every 4 years, except for century years not divisible by 400. For example, 2000 was a leap year but 1900 was not. The calculator handles all of this automatically.
Does this calculator account for US holidays?
Yes. The results show how many US federal holidays fall within your selected date range, along with the specific holiday names and dates. This helps with project planning and deadline calculations.
What date is 90 days from today?
Use the 'Add or Subtract Days' section below the main calculator. Enter today's date, set the amount to 90 and the unit to days, and choose 'add'. The result date is calculated instantly. You can also subtract days or use weeks, months, and years as units.