How to Calculate Age Difference by Birth Date
A practical guide to finding the exact age gap between two dates without losing days around month boundaries.
The most reliable way to calculate an age difference is to compare the earlier birth date with the later birth date, then borrow from months and years only when the day or month value goes negative.
This matters because months do not all have the same number of days. February, leap years, and end-of-month dates can make a simple subtraction inaccurate.
Use the calculator on the homepage when you need an exact result in years, months, and days.