Guides
How courts, banks, carriers, employers, and contracts actually count days — including the edge cases that cause disputes, and the places where conventions genuinely differ.
How to Count Business Days (Without Missing a Deadline)
The rules banks, courts, and couriers use to count business days — including what happens with weekends, holidays, and cut-off times.
The 90/180-Day Schengen Rule, Explained With Examples
How the Schengen short-stay rule actually counts days, why the 180-day window is "rolling", and how to compute your remaining days.
Why Easter Moves: How the Date Is Actually Determined
Easter can fall anywhere from March 22 to April 25. Here's the real rule, the ecclesiastical moon, and how to compute it.
90-Day Probation Periods: How to Count Them Correctly
Whether a probation period is 90 calendar days or 3 months matters more than you think. How employers and employees should count.
Leap Years, DST, and Other Ways Date Math Goes Wrong
The five classic bugs in day counting — leap years, DST, month lengths, inclusive counting, and timezones — and how to avoid each.
Net 30, Net 60, Net 90: How Invoice Payment Terms Really Work
What net 30, net 60, and net 90 really mean: when the clock starts, the 2/10 discount math, late-fee conventions, and how to set terms that get you paid.
Return Windows: How 14, 30, and 90-Day Policies Actually Count
When does a 14, 30, or 90-day return window actually end? How retailers start the clock, why calendar days rule, and how to count your deadline safely.
Pregnancy Weeks to Months: How the 40-Week Calendar Works
Why pregnancy is counted as 40 weeks from the last period, how weeks map to months and trimesters, and how a due date is calculated with Naegele's rule.
Billing Cycles: Why 'Monthly' Isn't Always 30 Days
Why monthly billing runs 28-31 days: calendar-month renewals, date clamping, credit card grace periods, proration, and honest annual-vs-monthly price math.
When Will My Transfer Arrive? ACH, Wire, and Same-Day Timing Rules
How ACH, Same Day ACH, and wires actually schedule: Nacha cutoff windows, Fed holiday rules, and why five business days can span eight calendar days.
How Court Deadlines Count Days (and Why Rule 6 Matters)
How FRCP Rule 6(a) counts federal deadlines: skip day one, count weekends, roll the last day, add three for mail — with dated 2026 worked examples.
90-Day Probation Periods: How to Count Them Correctly
Why 90 days and three months differ by up to three days, which day counts as day one, and how probation, benefits and notice clocks run separately.
Counting a Medication Course: Day 1, Doses, and Refills
How medication day counts actually work: inclusive Day 1, days supply vs days elapsed, 28/30/31-day pack drift, and refill-too-soon thresholds.
Notice Periods: How to Count Backwards Without Missing the Deadline
Count notice periods backwards: why 30 days, one month and end-of-period are different dates, and how to find your last safe send date.
Why "3-5 Business Days" Delivery Never Means 5 Days
Why '3-5 business days' never means five calendar days: handling time, dispatch cutoffs, carrier weekend rules, holidays, and customs delays.
Free Trials: The Exact Moment You Get Charged
Free trials charge at the exact clock time you signed up, not end of day — how to find your true last safe cancellation moment.
The Six-Month Passport Rule, Counted Properly
How the six-month passport rule is actually counted: entry vs departure wording, Schengen's 3-month and 10-year tests, and renewal lead time.
Fiscal Quarters: Why Q1 Is Not Always January
Why Q1 means October for Washington and February for retailers: fiscal year conventions, 53-week years, and turning quarter labels into dates.
How Limitation Periods Are Counted (Accrual, Tolling, Discovery)
How limitation periods are actually counted: accrual, the discovery rule, tolling, statutes of repose, and last-day rollover.
School Calendars: Instructional Days, Terms, and the 180-Day Rule
How US school calendars count instructional days and hours, term lengths by system, snow-day waivers, and the 10% chronic absenteeism rule.
Evergreen Contracts: Counting the Window You Must Not Miss
How auto-renewal notice windows are counted: which date the anniversary hangs off, both edges of the window, receipt rules, and a reminder ladder.