Date Calculator
Calculate the difference between dates or add/subtract time periods from any date
How to Use This Date Calculator
- Choose 'Days Between' to find the difference between two dates, or 'Add/Subtract' to calculate a future/past date
- Enter your start and end dates, or start date and time period to add/subtract
- Toggle 'Include end day' if you need inclusive counting
- Optionally exclude US holidays or use business days only
- Click the calculate button to see results
Example: Project deadline: January 15 to March 31 is 75 days apart (76 with inclusive counting). If working business days only, that's about 53 work days. Adding 90 days to February 3 gives you May 4.
Tip: For legal and financial deadlines, always clarify whether the count is inclusive or exclusive, and whether weekends/holidays are excluded.
Why Use a Date Calculator?
Date calculations are essential for deadlines, contracts, project planning, and scheduling. Getting dates wrong can have serious consequences for legal compliance and project delivery.
- Calculate contract deadlines and notice periods
- Plan project timelines accounting for weekends and holidays
- Determine payment due dates for invoices
- Calculate statute of limitations for legal matters
- Schedule events and count down to important dates
- Calculate escrow periods and real estate closing dates
Understanding Your Results
Results show the date difference in multiple formats plus a detailed breakdown. For add/subtract operations, you get the resulting date and day of week.
| Result | Meaning | Action |
|---|---|---|
| Calendar days | All days including weekends | Standard for general time periods |
| Business days | Weekdays only (Mon-Fri) | Used for work-related deadlines |
| With holidays excluded | Weekdays minus federal holidays | Most accurate for business scheduling |
| Inclusive vs exclusive | Include end day in count or not | Legal docs specify which method applies |
Meaning: All days including weekends
Action: Standard for general time periods
Meaning: Weekdays only (Mon-Fri)
Action: Used for work-related deadlines
Meaning: Weekdays minus federal holidays
Action: Most accurate for business scheduling
Meaning: Include end day in count or not
Action: Legal docs specify which method applies
Note: Holiday exclusions use US federal holidays. For other countries or company-specific holidays, manual adjustment may be needed.
About Date Calculator
Formula
Date difference = End Date - Start Date (with optional adjustments) The calculation accounts for varying month lengths and leap years. Business days iterate through each day and skip non-working days.
Current Standards: US federal holidays include 11 fixed and floating dates. Some float (Thanksgiving = 4th Thursday of November). When a holiday falls on a weekend, it's observed on the nearest weekday.
Frequently Asked Questions
What's the difference between inclusive and exclusive counting?
Exclusive counting (default) counts days between dates: Jan 1 to Jan 3 = 2 days. Inclusive counting includes both end points: Jan 1 to Jan 3 = 3 days. Legal documents typically specify which method applies. 'Within 30 days' usually means exclusive; '30 days from date' starts counting the next day.
How does adding months work with different month lengths?
Adding 1 month to January 31 gives February 28 (or 29 in leap years), not March 3. The calculator stays within the target month. This can mean 'one month' varies from 28 to 31 days. For consistent intervals, consider adding specific numbers of days instead.
Why might my business day count differ from my employer's?
This calculator uses US federal holidays. Your company may observe additional holidays (day after Thanksgiving), different holidays (state-specific), or no holidays at all. Some industries work weekends. Adjust the result for your specific situation.
How do I calculate dates for other countries?
The holiday exclusion feature uses US federal holidays only. For other countries, use the basic calendar day or business day calculation, then manually subtract that country's holidays. Remember that some countries have different weekend days (Friday-Saturday in some Middle Eastern countries).
Does the calculator handle daylight saving time?
The calculator works with calendar dates, not times, so DST doesn't affect results. When DST begins, one day is 23 hours; when it ends, one day is 25 hours. But for date counting purposes, each is still counted as one day.