How to Use This Age & Next Birthday Calculator

1. Enter the person’s Date of Birth
2. Enter the “As of Date” (defaults to today if left empty)
3. Click Calculate
4. View the exact age in years, months, and days
5. See how many days remain until the next birthday

How Age is Calculated (Formula)

The calculator subtracts the birth date from the “as of” date:

Age = (As of Date) — (Date of Birth)
→ Years, Months, and Days separately

If the birthday hasn’t occurred yet in the current year, it counts the remaining days until the next birthday.

Real Example

Date of Birth: March 15, 1990
As of Date: May 30, 2026

Result:

• Age: 36 years, 2 months, 15 days
• Days until next birthday: 289 days (until March 15, 2027)

Why Use This Age Calculator?

• ✅ Free & Unlimited — No signup required
• ✅ Accurate — Accounts for month lengths and leap years
• ✅ Flexible “As of Date” — Calculate age at any past or future date
• ✅ Next Birthday Countdown — Know exactly how many days until the next celebration
• ✅ Mobile Friendly — Works on all devices

Frequently Asked Questions

How is age calculated in years, months, and days?

The calculator subtracts year, month, and day separately. If the day of birth hasn’t occurred yet in the “as of” month, it borrows days from the previous month. If the birth month hasn’t occurred yet in the year, it borrows a full year.

What happens if I leave “As of Date” empty?

The calculator automatically uses today’s date. This gives you the current age and days until the next birthday.

Does this calculator work for any date in the past or future?

Yes — you can enter any “As of Date” to calculate age at that specific point in time (e.g., age at graduation, retirement, or any milestone).

Is the next birthday calculation accurate for leap years?

Yes — the calculator correctly handles February 29 birthdays. If the next year is not a leap year, the birthday is considered March 1 for calculation purposes.

Can I use this for legal age verification?

This calculator provides estimates for informational purposes. For legal documents, always verify with official records or government systems.

Related Calculators

• Date Add/Subtract & Difference Calculator — Add or subtract days from any date
• Working Days Calculator — Count business days (Mon–Fri) between two dates
• Retirement Calculator — Plan your retirement age and savings
• Days Until Christmas Calculator — Countdown to December 25

Disclaimer: This age calculator provides estimates based on standard date difference logic. For legal, medical, or official age verification, always consult primary documents or authorized agencies.