Age and date difference calculator
Get an age in calendar years, months and days, plus the total duration in days, weeks and hours.
Enter your values, then calculate.
Your calculation stays in your browser.
The formula, explained
completed years + complete months + remaining daysConvention: a February 29 birthday falls on February 28 in non-leap years. Days are measured between UTC calendar dates, avoiding daylight-saving shifts. This does not determine legal age.
An example to check
Using the starting values below, the calculation gives:
Calendar age and elapsed days — 9,699 days elapsed between the two dates. The detailed age uses completed calendar years and months.
Months vary in length. Displayed hours use 24-hour days without a birth time or daylight-saving adjustments; they are not an exact elapsed-time measurement.
How to use this tool
Check the required inputs: birth date or start date, end date.
Choose the units and options that match your task. Calculate, check the result and use Copy or Print to keep a record. Rounding applies to the display; keep more precision in intermediate steps.
Calendar age and elapsed time
A month can have 28, 29, 30 or 31 days. Calendar age is therefore split into completed years and months, rather than divided by an average month. Total elapsed days are shown separately.
Where are my inputs processed?
Calculations run in your browser. Form values are not sent to Analytics. Copying, printing, sharing or opening an external service is your choice.
Method and interface checked on 2026-09-19 · Report an error