Costs
Country calendars mistakes, and the fixes that hold
Nine country calendars mistakes: assuming a Saturday and Sunday weekend, copying resolved dates for a rule-based closure, and treating a country as a timezone.
Archive
September 2026
Rules
Fifteen worked examples of business day counting across stacked closure layers
Fifteen worked examples over one invented three-layer closure arrangement in March 2027, counting and stepping business days with the arithmetic shown.
Guides
Spreadsheet and API tools holidays 2027: criteria, no dates
Spreadsheet and API tools holidays 2027: criteria for one closure list in Excel, Sheets, and Nager.Date, versioning it, and why no dates are listed here.
Rules
Spreadsheet Date and Workday Counting Mistakes
Spreadsheet date and workday-count mistakes: text dates, locale-dependent imports, midnight shifts, serial values, endpoint rules, and closure ranges.
Costs
Excel date serials and the 1900 and 1904 epochs: spreadsheet and API date handling
Excel date serials, the 1900 and 1904 epochs, text date traps, and spreadsheet and API tools that move dates without shifting or corrupting them.
Industry
Spreadsheet and API Tools: Google Sheets Date Settings
Spreadsheet and API tools in Google Sheets can reinterpret dates through file time zone and locale settings, serial values, and API response formatting.
Rules
Spreadsheet and API tools formula testing for parity
Spreadsheet and API tools formula parity: Excel NETWORKDAYS against Nager.Date, four pinned conventions, sixteen boundary cases, and the 1900/1904 epoch trap.
Guides
Testing an SLA deadline clock: the checks worth running before you trust it
What an SLA deadline clock has to model before any calculator is fit for it: windows, zones, pause rules, clock changes, and four acceptance tests to run.
Industry
SLA deadline mistakes: the blind spots that make two teams read the clock differently
Nine SLA deadline mistakes that leave two parties calculating different things: mixed units, undefined pauses, the wrong timestamp, and a stale calendar.
Rules
Federal Holiday Business Day Counting: Project Dates
Federal holiday business day counting with a real 2025 Memorial Day example, the one-day date shift, and a formula for rebuilding the schedule.
Industry
Before you act on SLA deadline calculators formula
The SLA deadline calculators formula: walk the schedule to find a due moment, keep a segment ledger for pauses, and handle the two boundaries that break both.
Rules
SLA deadline clocks: what your contract must say about calendars and closures
SLA deadline clocks depend on contract terms: which calendar is named and versioned, rest days, substitution, mid-term changes, and what to store per clock.
Industry
5 things worth knowing about state calendars holidays
State calendars in 2027: how a sub-national closure is enacted and published, why it can bind one class of body and not another, and why no date appears here.
Maintenance
State calendar mistakes that quietly move a real deadline without notice
Nine state calendars mistakes that quietly produce a wrong deadline, from treating the national list as complete to trusting a tool's built-in data.
Features
Building state calendars in Excel with one column per layer
State calendars in Excel: one column per layer, a union built with a formula rather than by hand, and the lookup that picks the right layers for a row.
Guides
Working days per month mistakes: the traps and the way around them
Working days per month mistakes: the average-month divisor, the inclusive month edge, the leap-year February, and other errors that survive review.
Reviews
Six inputs a workday calculator needs before it can answer
Six inputs a workday calculator needs first, what each missing closure layer or default does to the answer, and how to check the skipped days by hand.
Maintenance
The set formula for combining closure layers into a single workday count
Set rules for layering closure calendars into a workday count: rest days first, then the union of every applicable list, with a hypothetical worked March example.
Reviews
Country calendars in Google Sheets: taming the weekend argument first
Country calendars in Google Sheets: the weekend argument that most sheets never set, one closure range per country, and the parsing trap in imported dates.
Maintenance
Country calendars holidays: a review routine for each new national closure list
A step-by-step routine for reviewing a new national closure list against the old one, so country calendars holidays changes never move a count unseen.
Industry
What separates the strong country calendars examples from the weak
Country calendars examples compared by name, from Canada and the United States to Saudi Arabia, showing where each one quietly moves a deadline.
Guides
Multiple working calendars in one Excel sheet: WORKDAY.INTL weekend strings
How to hold several working calendars in one Excel sheet: WORKDAY.INTL weekend strings, a calendars and closures table lookup, and what breaks.
Costs
The open-day formula with rest-day sets: five weekend conventions and cross-border spans
The open-day formula takes the rest-day set as an argument, with 2027 spans under five weekend conventions and the cross-border case for two ends.
Reviews
9 working-hours mistakes that produce a wrong deadline without warning
Nine working hours mistakes that cause wrong deadlines: dividing elapsed time by eight, the missing window zone, and the day that is not 24 hours long.
Rules
Alberta Energy Regulator filings, counting business days in Calgary and Edmonton
AER filing business days Alberta: how the regulator counts submission deadlines against Alberta statutory holidays, with worked examples for Calgary and Edmonton.
Industry
Bank of Canada payment system dates: Lynx windows and holidays
Bank of Canada payment system dates: Lynx settlement windows in Eastern time, federal holiday closures, how ACSS settles through Lynx, and your bank's cutoff.
Guides
Canada Post delivery standards business days: how they count
Canada Post delivery standards business days start at the acceptance scan. It covers weekends, statutory holidays, local cut-offs and cross-border handover.
Rules
CRA business day deadlines: GST/HST and corporate dates
CRA business day deadlines for GST/HST and corporate returns: find the statutory date, check CRA holidays, and apply the weekend or holiday shift.
Guides
Does Montreal payroll follow Quebec holiday counting under the Civil Code?
Montreal payroll runs on two clocks: Civil Code payment terms between businesses and Quebec labour standards for employees, and holidays move each one differently.
Guides
4 rules for counting Nova Scotia and Newfoundland business days in Halifax and St. John's
Nova Scotia and Newfoundland business day counts need both provincial holiday lists, plus port and offshore calendars that close on days the province is open.
Guides
Ottawa's federal public service calendar for contractors counting business days
Federal public service holidays in Ottawa do not match Ontario's statutory list, and that gap moves contract and SLA deadlines by a day or more.
Rules
Quebec Construction Holiday Business Days: Schedule Impact
Quebec construction holiday business days can distort project schedules because standard holiday lists omit the closure. Learn the date rule and adjust counts.
Industry
US and Canada holiday calendars compared for cross-border contract dates
US Canada contract business days turn on two holiday calendars. Compare federal and provincial dates to stop SLA and payment terms slippage each year.
Guides
Working hours API: the four operations and their responses
A working hours API answers four questions: duration, add, is_open and next_open. Edge rules, a response with segments, and test vectors for each.
Costs
Working hours holidays: a dated, sourced directory
Working hours holidays in 2027: the closure dates that move deadlines, who publishes each one, and how to check the list your filing depends on.
Features
Working hours Google Sheets: setup and timezone trap
Set up working hours Google Sheets formulas with Open and Close ranges, holiday dates, elapsed-time formatting, and the spreadsheet and Apps Script time zones.
Rules
A Guide to CRA Business Day Deadlines and Counts
CRA business day deadlines and counts, explained stage by stage: filing dates, payments and objections, plus the shift rule that moves a due date.
Rules
A Guide to Federal Holidays in Business Day Counts
A federal holiday business day calendar drifts when the OPM and Federal Reserve lists are mixed up. Two closures separate them, and both can move a deadline.
Rules
Federal vs State Court Filing Deadlines: Counting Business Days
Federal vs state court filing deadlines: how FRCP 6 and state rules count business days, holidays and mail service differently, and where each count goes wrong.
Rules
IRS response deadlines: calendar days, not business days, and when dates move
Most IRS response deadlines count calendar days, not business days. This explains start dates, weekend and holiday moves, postmark proof, and missed dates.
Guides
How to Count USPS Business Days for Delivery Estimates
A USPS business day delivery calculator counts Monday to Saturday, not federal days. Here is the one rate worth tracking and the point where you act on it.
Rules
Working days per year API: the version that survives contact with reality
A working days per year API is a caching problem: pin the calendar version, define which year you mean, and make the response carry its own provenance.
Reviews
Working days per year holidays with verified dates and sources
Working days per year in 2027 come down to the named public holidays landing on weekdays, their exact dates, and the official sources verifying each one.
Industry
Two ways to total working days in a year using Excel formulas
Working days per year in Excel: a single NETWORKDAYS call, the SUMPRODUCT alternative that shows its work, and the checks that catch a wrong answer.
Costs
Working Days Per Year Examples: Fiscal Baseline Checks
Working days per year examples: build a fiscal-span weekday baseline from monthly counts, subtract the federal holiday list for three spans, and reverse-check a reported total.
Features
Monday to Friday totals for any year: why the count is only 260, 261 or 262
How to count Monday to Friday weekdays in a year: 52 weeks give 260, leftover days add one or two, and the total is 260, 261 or 262. The table covers all start days.
Features
What matters most in working days per month holidays
Working days per month in 2027: how a monthly closure list is sourced, versioned and applied, and why this page states no holiday date for any country.
Rules
Add business days: three start conventions and fifteen worked cases excluding the start
Fifteen worked add business days cases excluding the start, plus how the three start-day conventions and a closure really move an actual deadline.
Maintenance
A working brief on add business days formula as of 2027
What the WORKDAY formula really does at the edges: rest-day starts, zero and negative counts, silently ignored text closures, and a hand method that matches.
Industry
How closures change an add-business-days count in 2027
Add business days in 2027: what a closed day costs a count, the four ways two closure lists honestly disagree, and how to make an answer reproducible.
Guides
Best subtract business days tools 2027: facts and context, explained properly
Six named tools that count backward from a deadline, what each one does with weekends and regional public holidays, and where the counting rules come from.
Rules
Country calendars: three origins of a closed day
Country calendars: the three kinds of closed day, how a national list is published, and the fields to capture before you rely on one for a deadline.
Maintenance
Days between dates API: signal versus noise
Designing a days between dates API: plain dates against moments, the request and response fields worth echoing, and vectors that catch a merged type.
Reviews
Days between dates by country: the directory, with corrections
Counting days between dates across a border turns on the working week, whose closure list applies, the governing zone, and which endpoints count.
Maintenance
Days between dates: the method a calculator runs and the divide by seven check
The method a days between dates calculator runs, written for paper: day of year subtraction, leap years, a divide by seven check, and when to trust a tool.
Costs
Days between dates in Excel: subtraction, times, DATEDIF and NETWORKDAYS
Excel formulas for days between dates: subtraction and inclusive counts, times in cells, DATEDIF units, NETWORKDAYS and WORKDAY, and what the sheet cannot decide.
Rules
Days between dates formula: build the day number and test it
A days between dates formula built on a March-first day number, tested on leap days and century years, then reconciled with a spreadsheet's NETWORKDAYS.
Guides
Days between dates holidays: past and future windows
How a closure changes a days between dates count, and why a window that has closed and one that has not must be counted against different lists.
Features
How SLA deadline calculators determine due dates
SLA deadline calculators turn contract rules into due moments; see how business-hour calendars, pauses, time zones, and boundary rules change the result.
Reviews
Spreadsheet or API: where the calendar should actually live
Spreadsheet or service: where the calendar lives, the contract a date must satisfy crossing between them, and one test set both sides should pass alike.
Guides
Who actually publishes the state calendars that set a deadline?
Who publishes the state calendars that actually govern a deadline, why the personnel list is the trap, and how to build one office's calendar properly.
Costs
Subtract business days API: direction, request fields, and response shape
How to design a subtract business days API: putting direction in its own field, the request fields it must carry, and what a response should echo back.
Industry
Subtract business days formula: WORKDAY and worked cases
How WORKDAY with a negative count subtracts business days: the three arguments, weekend strings for other weeks, and worked deadline cases.
Rules
Subtract Business Days Holidays 2027: U.S. Example
Subtract business days holidays 2027 with a U.S. example: how OPM’s observed July 5 closure shifts a backward count and which calendar should govern.
Maintenance
Notes on working days per month in Excel: NETWORKDAYS, EOMONTH and month edges
How to get working days per month in Excel with EOMONTH and NETWORKDAYS, what both-end counting does at month edges, and where weekend and holiday arguments break.
Guides
Working days per month formula: test vectors and checks for your code
Test a working days per month formula before you trust it: edge spans, a month-by-month 2027 sum, a day-by-day sweep and the off-by-one bugs.
Maintenance
Why a year's working day total starts with 260, 261 or 262 weekdays
Explains why a year's working day total starts with 260, 261 or 262 weekdays, how leftover days decide the count, and why closures and payroll divisors sit on top.
Industry
How to count working hours between two timestamps
Count working hours between two timestamps by clipping each day's window to the interval, with seven worked intervals and the same count in a spreadsheet.
Costs
Workday counts for a month: why length and starting weekday decide the total
Working days per month is 20 to 23 weekdays, decided by month length and start weekday: the rule behind it, a worked year, and where the count misleads.
Reviews
Days between dates: six honest answers to one simple-looking pair
One pair of days between dates, six honest answers: the unit, the endpoints, the calendar and the place that decide which number you were actually asked for.
Guides
Add Business Days: Four Assumptions to Set First
Before adding business days, identify the working week, closure authority, receipt cut-off and governing place, and record who can confirm each.