From the Blog
Long-form essays on age, calendars, demographics, and the everyday math of being human.
How to Calculate Your Exact Age (and Why Most People Get It Wrong)
Calendars are messy. Here is the right way to compute age in years, months, and days — by hand and by calculator.
April 12, 2026
9 min readChronological Age vs. Biological Age: What Each One Actually Measures
One is a number on a passport. The other is an estimate of how worn your body is. Here is how the two diverge.
April 4, 2026
7 min readWhy We Have Leap Years (and the Surprising Rule Almost Everyone Forgets)
The four-year rule is famous. The hundred-year and four-hundred-year rules are not — and they matter.
March 22, 2026
10 min readHow Accurate Is a Pregnancy Due Date? The Math Behind Naegele’s Rule
Only about 4% of babies arrive on the predicted day. Here is why — and how clinicians refine the estimate.
March 8, 2026
11 min readSchool Cut-Off Ages Around the World: Why Birthdays Decide Grades
A child’s month of birth can shape twelve years of schooling. A guide to global school-entry rules.
February 19, 2026
6 min readA Brief History of the Age Calculator
From abacus tables to ENIAC to the JavaScript engines in your browser today — how counting years became a one-tap problem.
February 4, 2026