Days Since and Date Difference Calculator
Count days since a past date, compare any two calendar dates, or calculate age from a birth date.
DaysWeeksAge mode
Choose dates to calculate.
Related guides: How to Calculate the Number of Days Between Two Dates
How this tool helps
Date differences come up in project planning, school assignments, invoices, event countdowns, subscriptions, and personal records. This calculator gives a quick human-readable difference between two calendar dates and includes an age mode for date-of-birth checks.
How to use it
- Choose standard difference mode when you already have a start date and an end date.
- Use age mode when the first date is a birthday and the second date should be today.
- Review both the exact day count and the year-month-day breakdown, since different tasks prefer different wording.
Practical tips
- Calendar months vary in length, so month and year breakdowns are best treated as human-readable estimates.
- For legal, payroll, medical, or compliance deadlines, confirm the counting rule required by the organization.
- If the end date is before the start date, swap the dates or treat the result as time remaining in reverse.
FAQ
Does it include the end date?
The main day count measures elapsed time between dates; add one day manually if your task counts both endpoints.
What is age mode for?
Age mode fills the end date with today and labels the result as an age-style calculation.
Does time zone affect the result?
The tool normalizes dates at local midnight, which is suitable for ordinary calendar comparisons.