Excel dates and workdays: ROC dates, calendar conversion and holiday limitations

Date data may look simple while actually mixing ROC years, Gregorian years, text values and Excel date serials. Workday calculations add another layer because weekends, public holidays, company shutdowns and shift schedules are not identical concepts.

ROC and Gregorian year conversion

In the common Taiwan ROC calendar, adding 1911 to the ROC year gives the Gregorian year. ROC year 115 corresponds to 2026. Real files, however, may use forms such as 115/8/19, 1150819 or text containing Chinese date labels, so a converter must interpret the input format rather than merely replace digits.

Separate dates from date-time values

Shipping, receiving and system logs may require hours, minutes and seconds. HR or expiry records may only need a date. Decide what information must be preserved before converting formats.

Weekdays are not an official work calendar

A basic workday calculator may exclude Saturday and Sunday, but that does not automatically account for public holidays, make-up working days, company-specific closures or rotating shifts. Calculations used for contracts, payroll, attendance or legal deadlines should be checked against the applicable official or organizational calendar.

Good uses for a simple workday tool

• Quickly estimate the number of ordinary weekdays in a range.
• Compare two scheduling options.
• Check whether input dates are reasonable before building spreadsheet formulas.
• Create an initial plan that will later be verified against a formal calendar.

Common date-field problems

Leading and trailing spaces, different separators and mixed cell formats can cause visually similar dates to behave differently. If sorting looks wrong, check whether the cells contain real date values or text.

WUCJ Tools date and workday functions are intended for data cleanup and preliminary calculation. When results affect legal rights, payroll, leave, contracts or official deadlines, confirm them with the relevant rules and official calendar.