To find how old you are in weeks, count the days since you were born and divide by 7. As a quick estimate, multiply your age in years by 52.18. A 30-year-old is about 1,565 weeks old, a 40-year-old about 2,087 weeks, and a baby celebrating a first birthday is 52 weeks old.
Below is an age-in-weeks chart, the exact method, and why weeks are the unit people use for babies and for thinking about a whole lifetime.
Age in Weeks Chart
| Age | Weeks old (approx.) |
|---|---|
| 1 year | 52 weeks |
| 2 years | 104 weeks |
| 5 years | 261 weeks |
| 10 years | 522 weeks |
| 13 years | 678 weeks |
| 16 years | 835 weeks |
| 18 years | 939 weeks |
| 21 years | 1,096 weeks |
| 25 years | 1,304 weeks |
| 30 years | 1,565 weeks |
| 35 years | 1,826 weeks |
| 40 years | 2,087 weeks |
| 50 years | 2,609 weeks |
| 60 years | 3,131 weeks |
| 65 years | 3,392 weeks |
| 70 years | 3,652 weeks |
| 80 years | 4,174 weeks |
| 90 years | 4,696 weeks |
Calculated at the average Gregorian year length of 365.2425 days (52.18 weeks). Your exact figure depends on your birth date and how many leap years you’ve lived through.
How to Calculate Your Exact Age in Weeks
- Count the total days from your date of birth to today, including the extra day in each leap year you’ve lived through.
- Divide by 7. The whole number is your age in complete weeks; the remainder is extra days.
Example: someone born on 1 January 2000 was 9,629 days old on 13 May 2026. 9,629 รท 7 = 1,375.6, so they were 1,375 weeks and 4 days old.
Counting days by hand is tedious and easy to get wrong around leap years. The free Exact Age Calculator shows your age in years, months, weeks, days, hours and seconds from your date of birth.
Why Babies Are Measured in Weeks
Doctors and parents track young babies in weeks because development changes quickly: a lot happens between week 6 and week 10. Many parents switch to months at around 3 months and to years at around 2. If your baby was born early, health professionals often use a corrected age (age from birth minus the number of weeks born early) to judge development milestones, usually until about age 2.
Your Life in Weeks
Weeks are also a powerful way to see a whole life at once. A 90-year life is about 4,700 weeks, few enough to fit on a single sheet of paper as a grid of boxes. Author Oliver Burkeman built a bestseller around the fact that an 80-year life is only about four thousand weeks (see our summary of Four Thousand Weeks).
Some milestones worth knowing: you turn 1,000 weeks old at about 19 years and 2 months, 2,000 weeks at about 38 years and 4 months, and 3,000 weeks at about 57 and a half.
See your own life as a grid of lived and remaining weeks with the free Life in Weeks Calculator.
Frequently Asked Questions
How many weeks old am I if I’m 30?
About 1,565 weeks. The exact number depends on your birth date and the leap years you’ve lived through, so it can differ by a week either way.
How many weeks are in a year?
52 weeks and 1 day in a normal year, or 52 weeks and 2 days in a leap year. On average that’s about 52.18 weeks.
At what age are you 1,000 weeks old?
At about 19 years and 2 months. 1,000 weeks is 7,000 days.
How many weeks old is a 6-month-old baby?
About 26 weeks. Exactly, it’s the number of days since birth divided by 7, which is 26 weeks for most 6-month-olds.
Get your exact age in weeks, days and even seconds with the free Exact Age Calculator.
Source: American Academy of Pediatrics (HealthyChildren.org): corrected age for premature babies.