Date Calculator
Add or subtract days, weeks, months, and years from any date. Find the difference between two dates.
Quick Answer
Use this calculator to add or subtract time from any date, or find the exact difference between two dates. Perfect for project planning, deadline calculation, and age determination.
Dr. Snezana Lawrence
Mathematical Historian
15+ years experience
PhD from Yale University. Published mathematical historian ensuring precision in all calculations.
Education
PhD in Mathematical History - Yale University
Table of Contents
How to Use the Date Calculator
Add Time to a Date
- Select "Add Time" mode
- Enter your starting date
- Enter years, months, weeks, and/or days to add
- Click Calculate to see the result
Subtract Time from a Date
- Select "Subtract Time" mode
- Enter your starting date
- Enter years, months, weeks, and/or days to subtract
- Click Calculate to see the past date
Find Date Difference
- Select "Date Difference" mode
- Enter the start date
- Enter the end date
- Click Calculate to see the difference
Common Use Cases
- Project deadlines: Calculate when a project will be due
- Contract dates: Find end dates for fixed-term agreements
- Age calculation: Determine exact age in years, months, and days
- Event planning: Count down days to an upcoming event
- Warranty expiration: Find when warranties expire
- Legal deadlines: Calculate filing and response deadlines
- Payment schedules: Determine future payment dates
Understanding Date Math
Date calculations involve several considerations:
- Leap years: February has 29 days every 4 years (with exceptions)
- Variable month lengths: Months have 28-31 days
- End-of-month handling: Adding 1 month to Jan 31 goes to Feb 28/29
- Order matters: Adding months then days differs from days then months
Quick Reference:
- 1 year = 365 days (366 in leap years)
- 1 month = ~30.44 days on average
- 1 week = 7 days
Frequently Asked Questions
How do I calculate a date X days from now?
Use the Add mode, enter today's date as the start date, enter the number of days you want to add in the Days field, and click Calculate. The result will show the future date.
How do I find how many days between two dates?
Use the Difference mode, enter both dates, and click Calculate. The calculator will show the total days and break it down into years, months, weeks, and days.
Does this calculator account for leap years?
Yes, the date calculator properly handles leap years when calculating dates. February 29 is correctly included in leap years.
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Dr. Snezana Lawrence
Mathematical Historian | PhD from Yale
Dr. Lawrence is a published mathematical historian with a PhD from Yale University. She ensures mathematical precision and accuracy in all our calculations, conversions, and academic score calculators. Her expertise spans computational mathematics and educational assessment.
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