Date Difference Calculator
Calculate the time between two dates in years, months, days, weeks, hours, and business days.
How to use this calculator
Enter a start date and an end date. The calculator shows the difference broken out in calendar terms (years, months, days), plus total days, weeks, months, hours, and business days. It handles reversed input (end before start) automatically.
Common uses
Project timelines, contract periods, lease terms, waiting periods, warranty expirations, relationship or employment anniversaries, countdown to a deadline, and figuring out days until an event. For business contexts, the business-days figure is particularly useful when SLAs or deadlines specify "5 business days" etc.
Why business days matter
A standard month has 20-22 business days depending on layout. Over a year, there are roughly 260 business days (365 - 104 weekend days - 10 or so US federal holidays). If you're calculating a deadline quoted in business days, use that figure — not total calendar days. For international projects, be explicit about which holidays you're excluding.
Leap years and the small discrepancies
From 2020-01-01 to 2024-01-01 is 1,461 days, not 1,460 — because 2020 and 2024 were leap years. From 2020-01-01 to 2023-01-01 is 1,096 days (365 + 366 + 365). Calendar-aware calculators (like this one) handle this automatically, which is why you might notice small differences from a naive "years × 365" estimate.
Inclusive vs exclusive day counts
One detail trips people up: should a range include both the start and end date, or just the gap between them? This calculator reports the elapsed days between the two dates — so January 1 to January 8 is 7 days. If your context counts both endpoints (some billing, rental, and legal "day count" rules do), add one to the total. When a contract says "within 30 days," confirm whether day zero is the event date or the day after before you trust a deadline.
Frequently asked questions
How are business days counted?▾
Business days = Monday through Friday, excluding weekends. Public holidays are NOT automatically excluded — they vary by country and year, so the calculator leaves that to you. For a precise 'working days' figure, subtract any observed holidays manually.
Does the order of dates matter?▾
No. The calculator automatically handles dates entered in either order and returns absolute (positive) differences.
Are totalDays and years × 365 the same?▾
Not quite. Leap years add a day every ~4 years, so 10 calendar years ≈ 3,652.5 days, not 3,650. The calculator counts actual calendar days elapsed, so small discrepancies versus 365 × years are expected.
Can I include time-of-day in the calculation?▾
The calculator uses dates (not times), treating each date as midnight UTC. If you need hour/minute precision for specific times, add or subtract the relevant offset to the date manually. For most use cases (project timelines, contract periods, anniversaries), date-level precision is enough.
How do I count the number of weekend days between two dates?▾
Subtract the business-days figure from the total-days figure — the difference is the number of weekend days (Saturdays and Sundays) in the range. Divide by two for an approximate count of full weekends. This ignores public holidays, which you'd subtract separately if you need true working days.
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