Notes on time.
Clear, practical guides on dates, time zones, and the small calculations that keep everyday life on schedule.
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Fresh from the journalThe Psychology of Deadlines: Why Counting Down Helps You Deliver
Missing deadlines is not a character flaw, it is predictable psychology. Meet the seven effects that govern how we handle time, and turn a simple countdown into work that actually ships.
All articles
17 more to exploreCounting Weeks for Projects, Pregnancy, and Paydays
A week is always seven days, yet a midwife, a payroll clerk, and a project manager each count them differently. Here is the arithmetic behind weeks, and the three places people reliably trip up.
Time03Scheduling Across Time Zones: A Survival Guide for Distributed Teams
When your team spans continents, "let's meet at 3" becomes a minefield. Here is how to find meeting times that work, avoid the daylight-saving traps, and communicate times so no one shows up an hour early — or a day late.
Guides04Leap Years Explained: Why 2100 Won't Be One
Everyone knows leap years come every four years — but that's not quite the rule, and the exceptions are why our calendar still lines up with the seasons after four centuries. Here is the full, surprisingly elegant logic.
Guides05Planning a Project Timeline: A Step-by-Step Guide with Dates
A good timeline is not a wish. It is arithmetic: real tasks, real dependencies, and business days counted honestly, with buffer built in on purpose. Here is how to build one that survives contact with reality.
Time06Measuring Elapsed Time: Stopwatches, Durations, and Getting It Right
From a runner's split to a server's response time, measuring "how long did that take?" is trickier than it looks. Here is the difference between a moment and a duration, why you should never use the wall clock, and how to add times up correctly.
Dates07Day of the Year and Ordinal Dates: The "Day 256" System Explained
Programmers celebrate day 256 as their holiday, and pilots file flight plans by "Julian date". Both use the day-of-year number — a count from 1 to 365 that quietly powers scheduling, aviation, and manufacturing.
Dates08What Day of the Week Were You Born? The Maths Behind the Answer
"Monday's child is fair of face..." — but first you have to know the day. Here is how calendars let you recover the weekday of any date, from the old nursery rhyme to the clever algorithm that does it in your head.
Guides09From Julian to Gregorian: How We Got the Calendar We Use Today
Our calendar is the product of two reforms sixteen centuries apart, an eleven-minute yearly error, and a decree that simply deleted ten days. Here is the whole strange story.
Dates10How Many Working Days Are in a Month? A Planner's Guide
Payroll, capacity planning, and delivery estimates all hinge on one deceptively tricky number: the working days in a month. Here is why it swings from 19 to 23, how to count it, and why the average month is not what you think.
Guides11The Complete Guide to Daylight Saving Time
Twice a year the clocks jump and half the world grumbles. Here is where the ritual came from, how "spring forward, fall back" actually works, why it wreaks havoc on software, and the case for and against keeping it.
Timers12How to Count Down to a Big Day (Without Losing the Plot)
A countdown turns a distant date into something you can feel. Here is how to set one up that actually motivates instead of stresses — the psychology of milestones, the maths of "days remaining", and the traps to avoid.
Dates13ISO Week Numbers Explained: Why Week 1 Isn't Always in January
Businesses run on "week 27" and "week 40", but the rules behind those numbers surprise almost everyone. Here is how ISO 8601 defines a week, why some years have 53 of them, and when January can sit in last year's week 52.
Time14What Is a Unix Timestamp? A Plain-English Guide
The single large number your apps use to store time, explained. Where the 1970 epoch came from, the seconds-vs-milliseconds bug, and why the year 2038 has a countdown of its own.
Time15Time Zones Explained: A Practical Guide to Converting Time Across the World
Offsets, UTC, daylight saving, and why India is half an hour out of step. A plain guide to naming a moment anywhere on Earth and converting it without the classic off-by-an-hour slip.
Dates16How to Calculate Your Exact Age in Years, Months, and Days
Your age in whole years is easy. Your age to the day is a borrowing puzzle, complete with end-of-month traps and leap-day birthdays. Here is the method that gets it right, worked through with a real date.
Dates17Business Days vs Calendar Days: Which One Does Your Deadline Mean?
A courier promises five business days, a bank promises three, a contract says thirty days' notice — and they do not mean the same kind of day. Here is how to tell them apart before a deadline surprises you.
Dates18How to Calculate the Number of Days Between Two Dates
Counting the days between two dates sounds simple — until an off-by-one error throws off a deadline. Here is how to get it right every time, by hand or in seconds.