Birthday Calculator
Calculate your exact age, find out how many days until your next birthday, discover fun facts about your birth date, and see your upcoming milestone birthdays.
How to Use the Birthday Calculator
- Enter your date of birth. The reference date defaults to today but you can change it to calculate age at any past or future date — useful for checking someone else's age on a specific day.
- Click Calculate to see your exact age in years months and days plus fun facts including the day of the week you were born your zodiac sign and how many days until your next birthday.
- The time lived section shows your age in every unit from days all the way to minutes so you can see just how much time you have experienced.
- Download the free PDF with your complete birthday report including upcoming milestone birthdays like your 40th 50th and beyond.
Example Calculation
DOB: March 15 1990 | Reference Date: March 21 2026
- Age: 36 years 0 months 6 days
- Total Days: 13,155
- Total Weeks: 1,879
- Total Hours: 315,720
- Total Minutes: 18,943,200
- Born on: Thursday
- Zodiac: Pisces
- Days Until Next Birthday: 359
- Next Birthday: March 15 2027 (turning 37)
- Milestones: 40th on Mar 15 2030 (1,455 days) | 50th on Mar 15 2040 (5,108 days)
Frequently Asked Questions
How is age calculated exactly?
Age is calculated by comparing the birth date to the reference date. Complete years are counted first then remaining complete months then remaining days. For example born March 15 1990 with reference March 21 2026 gives 36 years 0 months and 6 days. The day count adjusts for varying month lengths so February births are handled correctly in all cases.
What is my zodiac sign?
Your zodiac sign is determined by your birth date according to Western astrology. The 12 signs each cover approximately 30 days of the year. Aries runs March 21 to April 19 Taurus April 20 to May 20 and so on. People born on the boundary between two signs at the cusp may feel characteristics of both signs.
How many days have I been alive?
The total days calculation counts every calendar day from your birth date to the reference date including all leap years. A person born March 15 1990 has lived through 9 leap years by March 2026 giving 13,155 total days. This is the exact difference between the two dates measured in whole days.
Why does the months figure in my age seem lower than expected?
Age in months only counts complete calendar months. If your birthday is on the 15th and today is the 14th that final month is not yet complete so it is not counted. Only fully elapsed months appear in the months figure — the leftover days are shown in the days component. This is the standard way human age is measured.
What are milestone birthdays?
Milestone birthdays are culturally significant ages often celebrated with special events. The 18th marks legal adulthood in most countries. The 21st is the legal drinking age in the US. Round birthdays like 30 40 50 and 60 are commonly marked with big celebrations. The 65th is traditional retirement age. Turning 100 is called a centenary and is exceptionally rare — only about 1 in 5,000 people reach it.