Blog
Guides and explainers on dates, times, calendars, and how we measure them — the ideas behind the calculators.
How Long Is a Day, Really? (It's Not 24 Hours)
A full spin of the Earth takes 23 hours and 56 minutes — not 24. The missing 4 minutes explain why the night sky drifts through the seasons, and why our clocks track the Sun instead of the stars.
Is Midnight 12 AM or 12 PM? The Noon Problem
The 12-hour clock has a blind spot exactly where it matters most. 12:00 breaks the AM/PM logic, and the confusion has caused missed flights, insurance disputes, and legal headaches. Here is the fix.
Why Does February Have Only 28 Days?
Every other month has 30 or 31 days. February gets a stubby 28. The reason is a mix of Roman superstition, a winter nobody wanted to count, and an emperor who stole a day for his ego.
Why September Is the 9th Month When "Sept" Means Seven
September, October, November, and December literally mean 7, 8, 9, and 10 — yet they sit in positions 9 through 12. The mismatch is a 2,700-year-old fossil left by the Roman calendar.
Unix Time and the Year 2038 Problem
Most computers track time as a single number — seconds since January 1, 1970. It is elegant, timezone-proof, and quietly ticking toward a ceiling it will hit on January 19, 2038.
The 10 Days That Disappeared in 1582
In October 1582, people went to sleep on the 4th and woke up on the 15th. Ten days were deleted from the calendar on purpose — and different countries did it in different centuries, which quietly breaks date math to this day.
Why Does the Week Have 7 Days?
The week is the one time unit with no basis in astronomy — it matches nothing in the sky. Its seven days come from ancient planets, Roman gods, and a number people simply refused to abandon.
Why Are There 60 Minutes in an Hour?
We count time in 60s and 24s while everything else uses tens. The answer traces back 4,000 years to Babylonian astronomers and a number with an unusual superpower.
Why Pregnancy Is 40 Weeks, Not 9 Months
Pregnancy is measured as 40 weeks from the last period — about 9.2 months, not a neat 9. Here is why doctors count in weeks, where the extra time comes from, and how to convert.
Leap Years Explained: The Rule, the Exceptions, and Why February Gets a 29th Day
A leap year adds February 29 to keep the calendar aligned with Earth's orbit. Here is the exact rule, why 1900 was not a leap year, and how leap years affect date math.
How Many Working Days Are in 2026?
2026 has 261 weekdays and 250 working days after U.S. federal holidays. Here is the full month-by-month breakdown, plus how to count business days for any range.