Is the age calculation exact?

Yes. The calculator computes the exact difference between two dates, accounting for varying month lengths (28-31 days) and leap years. The result shows years, months, and days with no rounding.

What if my birthday is February 29?

If you were born on Feb 29 (a leap day), the calculator correctly handles your age. In non-leap years, your 'next birthday' countdown targets March 1. Your age in years is always calculated precisely.

Can I calculate the time between any two dates?

Yes. While it defaults to calculating age from a birth date to today, you can change both the start date and end date to find the exact time between any two dates in history or the future.

How are months calculated when dates don't align?

If the day of the target date is before the day of the birth date in the current month, the calculator borrows from the previous month. For example, from Jan 31 to Mar 2 is 1 month and 2 days (not 1 month and 1 day).

Why does my age in days not match years × 365?

Because leap years add extra days. Every 4 years (mostly) has 366 days instead of 365. A 20-year-old has lived approximately 7,305 days, not 7,300, due to 5 leap years in that period.

Can I use this to calculate retirement dates?

Yes. Enter your birth date and set the target date to when you turn your retirement age (e.g., 65 or 67). The calculator will show exactly when you reach that age and how many days until then.

How accurate is the 'weeks lived' calculation?

It's exact. Total weeks = total days ÷ 7. This is useful for tracking milestones (some cultures celebrate every 100 weeks, or parents track baby age in weeks).

general

Age Calculator

Calculate your exact age from your date of birth. See your age in years, months, days, weeks, and hours. Find the precise time between any two dates.

Last updated: March 31, 2026

Date of Birth

Select your birth date to see your exact age

How to Use This Calculator

Enter your date of birth (or the start date) using the date picker.
Optionally change the 'Calculate to' date if you want to find the age at a specific date rather than today.
Click Calculate to see your exact age.
Review the detailed breakdown showing years, months, days, total days, total weeks, and next birthday countdown.

Real-World Examples

Calculating Age for Legal Documents

You were born on March 15, 1995, and need to verify your age for a passport application on October 5, 2025.

Result: Age: 30 years, 6 months, 20 days. Total days: 11,161. Next birthday in 161 days. You meet the age requirement.

Anniversary Date Calculation

Your company was founded on June 1, 2010. You want to know exactly how long it's been operating as of January 1, 2026.

Result: 15 years, 7 months, 0 days. Total: 5,693 days or 813 weeks. Approaching the 16-year milestone.

School Enrollment Age Check

A child born on September 30, 2020, needs to be exactly 5 years old by September 1, 2025, to start kindergarten.

Result: On Sept 1, 2025: 4 years, 11 months, 2 days old. Does not meet the 5-year requirement. Must wait until next year.

Common Mistakes to Avoid

Forgetting that age in years only increments on your birthday, not at year-end.
Miscounting months when the target day is earlier in the month than the birth day.
Not accounting for leap years when calculating total days manually.
Assuming all months are 30 days when doing mental math (they range from 28-31).

The Formula

Age = Target Date - Birth Date, accounting for variable month lengths and leap years. Total days = difference in calendar days. Next birthday = next occurrence of birth month/day after target date.

Frequently Asked Questions

The calculator uses JavaScript's Date object which correctly accounts for leap years. February 29 birthdays are calculated as March 1 in non-leap years for the 'next birthday' countdown, while the age calculation itself is always precise to the day.