Date Calculator - Days Between Dates & Add/Subtract Days | Calcoul
Free online date calculator. Calculate days between two dates, add or subtract days, weeks, months, or years from any date. Includes workday calculations.
9 min readiAbout This Calculator
The date calculator is your essential tool for performing date arithmetic and calculating time spans between events. Whether you're counting down to a wedding, calculating the exact number of days until a project deadline, determining when a payment is due 90 days from now, or figuring out what date is 6 months from today, this comprehensive tool handles all your date calculation needs. Our calculator offers six versatile operations: finding days between two dates (including workday counts), adding or subtracting days, weeks, months, or years to any date. Unlike simple date counters, our tool provides detailed breakdowns showing years, months, weeks, and individual days, plus distinguishes between workdays and weekend days. Understanding date calculations is essential for project planning, financial projections, contract management, event planning, and everyday life. Stop counting on your fingers or flipping through calendars - let our calculator do the precise date math instantly.
?How to Use
- 1
Select the operation type from the dropdown menu. Choose 'Days between two dates' to find the time span, or select add/subtract options for date arithmetic.
- 2
For 'Days between' calculations: Enter your start date and end date using the date pickers. The order matters - negative results indicate the end date is before the start date.
- 3
For add/subtract operations: Enter your starting date and the number of days, weeks, months, or years you want to add or subtract.
- 4
Click 'Calculate' to see your results with a detailed breakdown including the resulting date, day of the week, and for date differences, a breakdown of years, months, weeks, and days.
- 5
Review the workday and weekend count for business planning purposes when calculating days between dates.
fFormula
Date difference is calculated by subtracting the start date from the end date, counting each full 24-hour period. For adding months or years, the calculator preserves the day of month when possible. If the target month doesn't have that day (like adding 1 month to January 31), it rolls to the last valid day. Leap years are properly handled - February 29 becomes February 28 when adding a year to a leap year date.
- Start Date
- The beginning date of your calculation
- End Date
- The ending date for difference calculations
- Days/Weeks/Months/Years
- The amount to add or subtract in arithmetic operations
Examples
Calculate Days Until a Deadline
From January 5 to March 15, 2026 is 69 days. This includes 49 workdays and 20 weekend days. Broken down: 2 months and 10 days.
Find Due Date 90 Days from Now
Adding 90 days to January 5, 2026 lands on April 5, 2026, which falls on a Sunday. Useful for calculating payment terms, warranties, or return windows.
Calculate Date 6 Months from Today
Adding 6 months to January 15 gives July 15, 2026. Month addition preserves the day of month (15th stays 15th) unless the target month has fewer days.
Find Date 2 Weeks Before Event
Subtracting 14 days (2 weeks) from June 15 gives June 1. Useful for setting reminder dates, booking deadlines, or RSVP cutoffs.
Use Cases
Project Management
Calculate project durations, milestone dates, and delivery deadlines. Track days until launch, compute sprint lengths, and plan phases by adding weeks or months to start dates.
Financial Planning
Determine payment due dates (net 30/60/90), calculate interest periods, track loan terms, and manage billing cycles. Essential for accounts receivable and payable management.
Legal & Contracts
Calculate statute of limitations deadlines, contract expiration dates, appeal periods, and notice requirements. Many legal deadlines are based on calendar or business days from an event.
Event Planning
Create timelines for weddings, conferences, and parties. Calculate RSVP deadlines, vendor booking cutoffs, and countdown days to the big day.
Health & Fitness
Track pregnancy due dates, medication schedules, recovery timelines, and fitness challenge durations. Calculate days since starting a health program.
Frequently Asked Questions
How do I calculate the number of days between two dates?
Does the calculator account for leap years?
How does adding months work when the target month has fewer days?
What counts as a workday in the calculations?
Can I calculate dates in the past?
How accurate is the date calculator?
What's the difference between 'add weeks' and 'add 7 days'?
How do I calculate a deadline that falls on a weekend?
Conclusion
The date calculator takes the guesswork out of date arithmetic, whether you're planning months ahead or counting days until an important event. With support for multiple operations - calculating date differences, adding or subtracting time units - this tool covers all your date calculation needs. The detailed breakdowns help you understand not just the answer, but the composition of time periods in terms of years, months, weeks, and days. For business users, the workday vs weekend distinction is invaluable for project planning and deadline management. Bookmark this page for quick access whenever you need to perform date calculations - your calendar counting days are over.