Age to Birthday Calculator
Enter your birth date and a target age to see the exact date of that birthday, along with how long you have left.
Use whole numbers (e.g., 16, 21, 65).
Defaults to now—adjust to plan from a different viewpoint.
Birth: 1/1/2000, 12:00:00 AM
Reference: 11/25/2025, 11:49:00 AM
Current age: 25 year(s), 10 month(s), 24 day(s)
You will turn 21 on Friday, January 1, 2021
That birthday has already passed. You next turn 22 on Saturday, January 1, 2022.
Time until next birthday: -1425 day(s)
How to Use This Calculator
Enter your birth details
Include time to account for birthdays that fall at specific hours.
Choose a target age
Common ages include 13, 16, 18, 21, 30, 50, 65, etc.
Review the milestone date
Mark it in your calendar and check how long until the celebration.
Formula
Target Birthday = Birth Date + (Target Age × 12 months)
Adjust end-of-month birthdays by rolling to the last valid day
Days Remaining = Target Birthday − Reference Date
Example: Born 2005-03-15 → 21st birthday is 2026-03-15.
Milestone Planning Ideas
- Schedule reminders for legal age changes (driving, voting, drinking, retirement).
- Plan marketing campaigns targeting customers approaching certain ages.
- Align financial planning (529 withdrawals, retirement benefits) with milestone birthdays.
- Create countdowns for significant celebrations and life events.
Frequently Asked Questions
Can I enter fractional ages?
This tool supports whole years for accuracy. For fractional years, calculate the nearest birthday and adjust manually.
What if the birthday already passed?
We flag that the milestone has passed and show when you will reach the next age.
Does it account for leap years?
Yes—adding months handles February and leap-day birthdays correctly.
Can I compare multiple ages?
Run the calculator for each age milestone you’re planning to monitor.