Find the number of days between two dates, or add/subtract years, months, and days from a start date. Helpful for deadlines, project plans, and age-related planning.
Date Calculator
Days between two dates
Add or subtract from a date
How to Use
- For difference: pick start and end dates, then Calculate Difference.
- For add/subtract: pick a base date, enter years/months/days, choose Add or Subtract, then Calculate New Date.
Formula
Difference in days = absolute difference of the two date values in days. Add/subtract uses calendar month and year rules in your browser.
Worked Example
Example: From Jan 1, 2026 to Apr 1, 2026 is 90 days. Jan 15, 2026 + 2 months = Mar 15, 2026.
What the Result Means
Use day counts for planning and the new date for deadlines. Business-day exclusions are not applied unless you adjust manually.
Important Notes & Limitations
- Does not skip weekends or holidays automatically.
- Month lengths and leap years follow standard calendar rules.
Frequently Asked Questions
Are weekends excluded?
No. Count is calendar days.
Time zones?
Dates are treated as local calendar dates without time-of-day.
Can I calculate age?
Yes—or use the dedicated Age Calculator for years, months, and days of age.
Leap years?
Yes, they are handled by the date engine.
Related Calculators
See also: Date Calculator, Age Calculator, Time Calculator.
Disclaimer: Results are approximate and for educational and informational purposes only. They are not financial, tax, medical, or legal advice. Verify important decisions with a qualified professional.