How many days
between two dates?
Enter any two dates to instantly calculate the difference
Written and maintained by Christin Bowles, founder of TidyCalcs.
Please select both dates.
Quick calculations
How date calculations actually work
Counting days between two dates involves more judgment calls than it looks like. Do you count the start date, the end date, both, or neither? This calculator defaults to counting the start date but not the end date (the most common convention), with a checkbox to include the end date when you need it — useful for things like counting the full length of a stay or rental period rather than just the gap between arrival and departure. Leap years are handled automatically, so a range spanning February 29 won't throw the count off.
Business days vs. calendar days
"30 days" and "30 business days" are very different timeframes, which matters for deadlines, notice periods, and project planning:
Checking "Exclude weekends" above converts the count to business days. Note that this excludes Saturdays and Sundays only — it doesn't automatically exclude public holidays, since those vary by country and region.
Common uses for date calculations
Beyond curiosity, day-counting comes up constantly in practical planning: tracking project or contract deadlines, calculating notice periods (a "30-day notice" clause, for example), estimating due dates from a known start date, planning countdowns to events like weddings or trips, and figuring out how long ago something happened for record-keeping or anniversaries.
Worked examples
These examples use 2026 dates, with the default rule of counting the start date but not the end date.
- October 1 to December 25, 2026: 85 days, which is just over 12 weeks. About 61 of those days are weekdays.
- 30 days from October 1, 2026: October 31, 2026. 90 days from October 1: December 30, 2026.
- 30 business days from Thursday, October 1, 2026: November 12, 2026, since weekends are skipped. Public holidays such as Veterans Day or Thanksgiving are not skipped, so add a day or two if they fall in your range.
- January 1 to December 31: 364 days in 2026, and 365 days in 2028, which is a leap year. Check "Include end date" if you want to count both the first and last day, which gives 365 and 366.
Why "one month" is not always 30 days
Months have 28 to 31 days, so counting in months and counting in days can give different answers. Thirty days from January 31, 2026 lands on March 2, but "one month" from January 31 is usually treated as the end of February. Contracts, leases and notice periods often say which one they mean. If the exact date matters, read the wording of the document, and count in days if it says days.
How to use the result for deadlines
- Notice periods: find out whether the clause counts calendar days or business days, and whether the day you give notice counts.
- Returns and warranties: check whether the clock starts on the purchase date or the delivery date.
- Project plans: use business days for work estimates, then add buffer for holidays and time off.
- Countdowns: to plan an event, convert the days into weeks so you can set weekly milestones. 85 days is about 12 weeks.
Common mistakes
- Forgetting whether the end date counts. This is the most common cause of being off by one day.
- Assuming business days include holidays off. This tool excludes only Saturdays and Sundays.
- Treating every month as 30 days. Use the exact dates instead.
- Ignoring time zones for legal deadlines. A deadline "by the end of the day" may depend on the local time zone stated in the document.
This calculator is for planning and is not legal advice. For contracts and filing deadlines, confirm the exact rule with the document or a professional.
Common questions
How do I calculate days between two dates?
Enter your start date and end date above, then click "Calculate days." The tool instantly shows the total days, weeks, months, and years between the two dates.
Does it count the start date or end date?
By default, the start date is counted but not the end date. Check "Include end date" to count both dates.
Can I exclude weekends from the count?
Yes — check the "Exclude weekends" option before calculating to count only business days (Monday through Friday).
How many days until a future date?
Set today as the start date and your future date as the end date. Use the quick buttons above for common dates like Christmas or New Year.
How many days since a past date?
Enter the past date as your start date and today as your end date. The calculator works for any date range, past or future.
Does the calculator account for leap years?
Yes — every date range automatically accounts for leap years, so a span that includes February 29 in any year will still produce an accurate day count.
What's the difference between calendar days and business days?
Calendar days count every day in the range, including weekends and holidays. Business days typically mean Monday through Friday only. Use the "Exclude weekends" option above to switch between the two — just remember it won't automatically skip public holidays.
Sources and further reading
For independent, authoritative information on this topic, these are good places to start:
- NIST: Official U.S. time — the official current date and time for U.S. time zones.
- U.S. Office of Personnel Management: Federal holidays — the official holiday calendar, useful when counting business days.