How the age calculator works
This age calculator from birthday computes the exact difference between your date of birth and today (or any target date). It counts full calendar years, then remaining months, then remaining days — the same way age is expressed in everyday life.
It also converts your age into total months, total weeks, total days, and total hours — answering questions like how old am I, "how old am I in days" or "how many months old am I" instantly.
Tip: Use the "Calculate age as of" option to find your age at any past or future date — useful for age verification, milestone tracking, or calculating age differences between two people.
Chronological age explained
Chronological age is the amount of time that has elapsed since a person's birth, measured by the calendar. It's the standard way age is determined worldwide for legal, medical, and social purposes.
Chronological age
Based on your date of birth. Fixed and objective. Used for legal and official purposes. This is what the calculator computes.
Biological age
Based on health biomarkers (telomere length, epigenetic clocks). Can be younger or older than chronological age. Estimated by medical tests, not calendars.
Age in different units
Here's what age 30 looks like in various time units — use the age in days calculator above for your exact numbers:
| Unit | Age 30 ≈ |
|---|---|
| Years | 30 |
| Months | 360 |
| Weeks | 1,565 |
| Days | 10,957 |
| Hours | 262,968 |
Weeks to months converter
Need to know how many months a certain number of weeks is? Since a month averages 4.345 weeks, divide the number of weeks by 4.345. Common conversions: 26 weeks in months is approximately 6.0 months. 21 weeks to months is about 4.8 months.
| Weeks | ≈ Months |
|---|---|
| 12 weeks | 2.8 months |
| 16 weeks | 3.7 months |
| 20 weeks | 4.6 months |
| 21 weeks | 4.8 months |
| 24 weeks | 5.5 months |
| 26 weeks | 6.0 months |
| 30 weeks | 6.9 months |
| 36 weeks | 8.3 months |
| 40 weeks | 9.2 months |
Formula: months = weeks ÷ 4.345 (average weeks per month).
How old am I if I was born in...?
Quick reference for common birth years (as of 2026). To calculate birth year from age, subtract your age from 2026. For exact age including months and days, use the calculator above.
| Birth Year | Age in 2026 |
|---|---|
| 2010 | 15 years old |
| 2006 | 19 years old |
| 2005 | 20 years old |
| 2004 | 21 years old |
| 2000 | 25 years old |
| 1995 | 30 years old |
| 1990 | 35 years old |
| 1985 | 40 years old |
| 1980 | 45 years old |
| 1975 | 50 years old |
If you were born in 2006, you are 20 years old in 2026 (2026 minus 2006 = 20). Your exact age depends on whether your birthday has already passed this year — use the calculator above for precision.
Leap year handling
A leap year occurs every 4 years (with exceptions for century years not divisible by 400), adding February 29 to the calendar. This calculator handles leap years automatically:
- Total days count includes all leap days within your lifetime
- If you were born on Feb 29, your age in years increments on March 1 in non-leap years
- The next birthday countdown uses the correct date (Feb 29 in leap years, Mar 1 otherwise)
Age calculation for legal purposes
Legal age matters for voting, drinking, driving, contracts, retirement benefits, and more. Key US age thresholds:
| Age | Milestone |
|---|---|
| 16 | Driving permit (varies by state) |
| 18 | Legal adult, voting, military service |
| 21 | Alcohol purchase |
| 59½ | Penalty-free 401(k)/IRA withdrawals |
| 62 | Early Social Security benefits |
| 65 | Medicare eligibility |
| 67 | Full Social Security retirement age |
FAQs
How is age calculated?
Age is calculated by counting the number of complete years, months, and days between your date of birth and the current date (or a specified date). A complete year is counted when the same month and day have passed. For example, someone born on March 15, 1994 is 32 years old on March 15, 2026, but still 31 on March 14, 2026.
What is chronological age?
Chronological age is your age measured strictly by the calendar — the number of years (and months/days) since the date you were born. It's the most common way age is expressed and is used for legal purposes, medical records, and official documents. It differs from biological age, which estimates how old your body is based on health markers.
Does the calculator account for leap years?
Yes. This age calculator uses actual calendar dates, so leap years (February 29) are handled correctly. If you were born on February 29, the calculator counts your birthday as occurring on March 1 in non-leap years when computing the 'next birthday' countdown. Total days are computed using exact date arithmetic, which includes all leap days.
How do I calculate my age in months?
Multiply your age in complete years by 12, then add any remaining months. For example, if you're 25 years and 7 months old, your age in months is (25 × 12) + 7 = 307 months. This calculator shows your exact age in months automatically.
How do I calculate my age in days?
The exact number of days depends on how many leap years fall within your lifetime. A rough estimate is years × 365.25, but for precision, use this calculator — it counts the actual days between your birth date and today, including all leap days. Someone who is 30 years old has lived approximately 10,957 days.
What is the legal age in the United States?
Key legal ages in the US: 16 — driving (varies by state), 18 — voting, military service, legal adulthood, 21 — alcohol purchase, 25 — car rental without surcharge (industry standard, not law), 62 — early Social Security, 65 — Medicare eligibility, 67 — full Social Security retirement age (for those born after 1960).
How old am I if I was born in 1995?
If you were born in 1995, you are 30 or 31 years old in 2026 — depending on whether your birthday has passed. For example, if your birthday is June 15, 1995, you turned 31 on June 15, 2026. Enter your exact birth date above for a precise calculation including months and days.
How to calculate age between two dates?
Use the 'Calculate age as of' field to enter any target date instead of today. The calculator will compute the exact time difference between your birth date and that target date. This is useful for determining age at a historical event, a future date, or for calculating the time between any two dates.
What is age verification?
Age verification is the process of confirming a person's age, typically for legal compliance (buying alcohol, tobacco, or accessing age-restricted content). Methods include checking government-issued ID, date-of-birth entry on websites, or third-party verification services. This calculator can help you verify exact age from a birth date.
Is age calculated from date of birth or date of conception?
In virtually all legal, medical, and social contexts in Western countries, age is calculated from the date of birth — not conception. Some East Asian age-counting systems (like the traditional Korean system) counted age from conception (adding roughly one year), but South Korea officially adopted the international system in 2023.
How do I calculate birth year from age?
Subtract your age from the current year. For example, if you're 30 years old in 2026, your birth year is 1996 (2026 − 30 = 1996). If your birthday hasn't occurred yet this year, subtract one more year — your birth year would be 1995.
Can I calculate a conception date from a due date?
As a rough estimate, subtract approximately 266 days (38 weeks) from the due date for an estimated conception date. For example, a due date of December 1 suggests conception around March 10. This is approximate — consult your healthcare provider for accuracy, as gestational age calculations can vary.
What is the full retirement age for Social Security?
For those born in 1960 or later, the full retirement age is 67. For those born in 1958, it's 66 years and 8 months. For those born in 1957, it's 66 and 6 months. Early retirement benefits are available at 62, but at a reduced amount. The retirement age is the same regardless of state — there is no separate retirement age in California, Texas, or any other state.