How to Add or Subtract Dates
- Enter your start date (defaults to today if not specified)
- Choose to Add or Subtract time periods
- Enter the time period you want to add or subtract (years, months, weeks, days, hours, minutes)
- Use "Quick presets" for common periods like 30 days, 3 months, etc.
- Optionally enable "Exclude Weekends" to calculate only business days
- Click "Calculate Result" to see your answer
Real-World Examples
Legal Deadline Calculation
If you need to file a response within 30 business days from January 15, 2024:
- Enter start date: January 15, 2024
- Select "Add" operation
- Enter 30 days
- Enable "Exclude Weekends"
- Result: The deadline date excluding weekends
Invoice Payment Terms
Calculate invoice due date for "Net 60" terms:
- Enter invoice date as start date
- Select "Add" operation
- Enter 60 days
- Enable "Exclude Weekends" if needed
- Result: Payment due date
Project Milestone Planning
Find when a project milestone will be reached:
- Enter project start date
- Select "Add" operation
- Enter the milestone period (e.g., 3 months, 12 weeks)
- Result: Milestone completion date
How Date Addition and Subtraction Works
Our date calculator uses precise date arithmetic to add or subtract time periods. The calculator accounts for:
- Variable month lengths: Different months have 28, 29, 30, or 31 days. Adding 1 month to January 31 results in February 28 (or 29 in leap years)
- Leap years: February has 29 days in leap years instead of 28
- Business days: When "Exclude Weekends" is enabled, only weekdays (Monday-Friday) are counted
- Year boundaries: Calculations correctly handle crossing year boundaries (e.g., adding months to December)
- Time components: You can add or subtract hours and minutes for precise time calculations
All calculations are performed in your browser in real-time. Your dates and calculations never leave your device, ensuring complete privacy and security.
Frequently Asked Questions
What is a date calculator?
A date calculator is a tool that allows you to add or subtract days, weeks, months, or years from any date, or calculate the duration between two dates. It's useful for planning deadlines, tracking project timelines, and calculating business days.
How do I add days to a date?
Enter your start date, select "Add" operation, enter the number of days (or weeks, months, years) you want to add, and click "Calculate Result". The calculator will show you the resulting date.
Can I subtract days from a date?
Yes! Select "Subtract" operation instead of "Add", enter the time period you want to subtract, and the calculator will show you the date that many days/weeks/months/years before your start date.
How do I calculate the duration between two dates?
Switch to the "Duration Between Dates" tab, enter your start date and end date, and click "Calculate Duration". The calculator will show you the total days, weeks, months, and years between the dates.
What are business days?
Business days are weekdays (Monday through Friday) excluding weekends and public holidays. This is important for legal deadlines, invoice payment terms, and project planning.
Can I exclude weekends from calculations?
Yes! Enable "Exclude Weekends" in the Advanced Options section. The calculator will skip Saturdays and Sundays when calculating dates or durations.
Can I exclude holidays from calculations?
Yes! Enable "Exclude Holidays" in Advanced Options and select your holiday region (US, UK, Canada, etc.). The calculator will skip public holidays in that region.
What holiday regions are supported?
Currently, we support United States (Federal Holidays), United Kingdom (Bank Holidays), Canada (Federal Holidays), and Australia (Public Holidays). More regions may be added in the future.
How accurate is the date calculator?
The calculator is highly accurate and accounts for variable month lengths (28-31 days), leap years, and business day exclusions. All calculations follow standard date arithmetic rules.
Can I calculate dates with hours and minutes?
Yes! The calculator supports adding or subtracting hours and minutes in addition to days, weeks, months, and years. This is useful for precise time calculations.
What happens when I add a month to a date that doesn't exist in the next month?
For example, adding 1 month to January 31 results in February 28 (or 29 in leap years). The calculator automatically adjusts to the last valid day of the target month.
Is the date calculator free to use?
Yes, our date calculator is completely free to use. No registration or payment is required. All calculations happen in your browser for privacy and security.
Can I share my calculation results?
Yes! Use the "Share" button to share your calculation result via your device's sharing options, or use the "Copy" button to copy the result to your clipboard.
How do I use quick presets?
Click "Quick presets" next to the Time Period label to see common time periods like 1 week, 30 days, 3 months, etc. Click any preset to automatically fill in the time period fields.
Can I calculate invoice due dates?
Yes! Enter your invoice date, select "Add", enter your payment terms (e.g., 30 days for Net 30), enable business days exclusion if needed, and calculate. Perfect for "Net 30", "Net 60", or other payment terms.
How do I calculate legal deadlines?
Enter the date you received notice, select "Add", enter the deadline period (e.g., 30 business days), enable both "Exclude Weekends" and "Exclude Holidays", select your jurisdiction, and calculate. This gives you the exact deadline date.
Does the calculator handle leap years?
Yes, the calculator correctly handles leap years. February 29 is included in leap years, and calculations crossing leap year boundaries are accurate.
Can I calculate project milestones?
Absolutely! Use the date calculator to add weeks or months to your project start date to find milestone dates. Enable business days exclusion if your project only runs on weekdays.