Date Difference Calculator — Days Between Two Dates
Free Date Difference Calculator — Days, Weeks, Months & Working Days
Find the exact difference between any two dates — in days, weeks, months, and years. Also shows working days (excluding weekends), the weekday each date falls on, and a plain-English summary. Instant results, formula always shown.
📅 Choose Two Dates
How to Use This Date Difference Calculator
Select any two dates using the date pickers above. Results appear instantly — no button click needed. You can also use the Quick Fill buttons to instantly load common date ranges like “Today to 1 month from now” or “New Year to Today.”
- The start date can be before or after the end date — the calculator always shows the absolute (positive) difference.
- Working Days counts only Monday through Friday. Public holidays are not automatically excluded — adjust manually for holidays in your region.
- The weekday displayed for each date helps you plan meetings, deadlines, and events around working schedules.
When Do You Need a Date Difference Calculator?
Project deadlines and planning
How many days until your project deadline? How many working days do you have left? Enter today as the start date and your deadline as the end date. The working days count shows exactly how many business days remain — critical for realistic project scheduling.
Contract and legal durations
Contracts often specify durations in days rather than calendar months. A 90-day notice period, a 180-day warranty, or a 30-day payment term all require precise date arithmetic. Our calculator gives you the exact end date — or the exact number of days between two dates — without ambiguity.
Age and milestone calculations
How long until someone turns 18? How many days has a company been in operation? How many days between two historical events? Date difference calculations appear in biography, history, law, and everyday planning. For age-specific calculations, also try our Age Calculator.
Travel and event planning
How many days until your vacation? How many weeks until a wedding or conference? Knowing the exact number of days — and which weekday the date falls on — helps you plan itineraries, book in advance, and set reminders at the right time.
HR and payroll
Calculating employee tenure, probation periods, leave entitlements, and notice periods all require date arithmetic. Working days is especially important here: a “10 working day” notice period has a very different end date than a “10 calendar day” notice period.
Date Difference Examples
Start: Aug 15, 2026 (Monday)
End: Oct 31, 2026 (Saturday)
Total days: 77 | Working days: 55
Notice given: Sep 1, 2026
90-day period ends: Nov 30, 2026
Working days in notice: 64
Today: Aug 15, 2026
Holiday: Dec 25, 2026
Days away: 132 | Weeks: 18.9
Founded: Jan 1, 2020
Today: Aug 15, 2026
Operating for: 6 years, 7 months, 14 days
Calendar Facts That Affect Date Calculations
Why “one month” is not always 30 days
Calendar months have different lengths — 28, 29, 30, or 31 days depending on the month and whether it’s a leap year. This is why our calculator shows both the total days and the month count separately. “One month from August 31” means September 30 (30 days), but “one month from January 31” means February 28 or 29 (28 or 29 days).
Leap years
A leap year occurs every 4 years (with rare exceptions at century marks). Leap years add February 29, making the year 366 days instead of 365. If your date range spans one or more February 29ths, the day count will reflect this correctly. Our calculator uses JavaScript’s timestamp arithmetic, which handles all leap years automatically.
Working days vs. calendar days
Our working days counter excludes Saturdays and Sundays. It does not exclude public holidays, as these vary by country and region. For exact business day calculations that account for holidays, manually subtract the number of holidays that fall within your date range from the working days total.
| Period | Calendar Days | Approx. Working Days |
|---|---|---|
| 1 week | 7 | 5 |
| 2 weeks | 14 | 10 |
| 1 month (approx.) | 30–31 | 21–23 |
| 1 quarter | 90–92 | 64–66 |
| 6 months | 181–184 | 130–132 |
| 1 year | 365–366 | 260–262 |
Frequently Asked Questions
How do I calculate the number of days between two dates?
Enter your start date and end date in the fields above. The total days figure appears instantly. The formula is: Total Days = (End Date − Start Date) converted from milliseconds to days by dividing by 86,400,000 (the number of milliseconds in one day).
Does this calculator count the start and end dates?
The calculator counts the gap between the two dates, not including the start date itself. So from August 1 to August 8 = 7 days (one week). If your context requires counting both the first and last day (as some legal contracts do), add 1 to the displayed total.
How are working days calculated?
Working days counts every Monday through Friday in the date range. Saturdays and Sundays are excluded. Public holidays are not automatically excluded because they vary by country — subtract any holidays in your region from the working days total for an exact business day count.
Can I use this calculator for dates in the past?
Yes. Enter any two dates, including past dates. The calculator works for any dates supported by the Gregorian calendar. You can calculate how many days ago something happened, how long an event lasted, or the difference between any two historical dates.
What if my end date is before my start date?
The calculator always shows the absolute (positive) difference between the two dates regardless of which is entered first. So swapping start and end date gives the same result.
How many weeks are in a year?
A standard year has 52 weeks and 1 day (365 ÷ 7 = 52.143). A leap year has 52 weeks and 2 days (366 ÷ 7 = 52.286). The exact week count between any two dates can be calculated using this tool.
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