Working days remaining in month

The starting date is included when it is Monday through Friday, while Saturdays, Sundays, and optional holiday dates are excluded. Because the calculation uses pure Gregorian calendar arithmetic in UTC and never reads the current clock, the same input always produces the same result. The response also separates calendar days, weekend days, and excluded holiday days so the final total is easy to audit.

Choose the date that begins the count

Provide one explicit calendar date in the strict YYYY-MM-DD form, such as 2026-07-20. That date establishes both the first possible working day and the month whose final day closes the interval. The calculation is inclusive, so a Monday starting date can contribute one day immediately; a Saturday starting date cannot. There is no hidden reference to today, a server timezone, or a browser locale. This makes the result appropriate for repeatable reports, scheduled workflows, tests, and records that may be recomputed later. The response includes the normalized starting date, the month-end date, and the number of calendar days inspected. It also states that the interval is inclusive. If you need a count that begins tomorrow, send tomorrow’s explicit ISO date rather than subtracting or relying on an unstated convention. Invalid dates, including impossible leap days or non-padded month and day values, are rejected instead of being silently corrected into another date. Years from 0001 through 9999 are handled with Gregorian leap-year rules.

Exclude weekends and holidays without double counting

Every date from the supplied day through month end is classified exactly once. Saturday and Sunday enter the weekend total. A Monday-through-Friday date listed in the optional holidays array enters the holiday total. All other weekdays enter the working-days total. Holiday entries outside the selected interval are valid but have no effect, which lets a caller pass a reusable annual or regional holiday list without trimming it for every request. A holiday that lands on a weekend does not reduce the answer twice, and duplicate holiday strings are treated as one exclusion. Each holiday must still be a real, strict ISO calendar date so malformed configuration is caught early. The API does not guess public holidays from a country code because holiday rules change by jurisdiction, employer, and year. Supplying the dates explicitly keeps the result transparent and deterministic. This tool models a conventional Monday-to-Friday workweek; it does not reinterpret Friday or Sunday as a weekend for region-specific schedules, and it does not apply half-day rules.

Read, verify, and automate the result

Use workdays_remaining as the primary answer. The supporting fields make it possible to verify the arithmetic: calendar_days equals weekend_days plus holiday_days plus workdays_remaining. The month_end field shows the exact boundary, which is especially useful for February and leap years, while holiday_days reports only weekday holidays that actually changed the total. This structure works well in payroll cutoffs, delivery planning, monthly capacity dashboards, service-level forecasts, and personal deadline calculations. For an automated integration, persist the input date and holiday list alongside the response so future reviewers can reproduce the same number. The endpoint costs $0.002 per request through the API, and each request represents one calculation regardless of the number of supplied holidays. Processing is local calendar arithmetic: it makes no network requests and does not consult a live holiday service. If your business calendar has shutdown periods, add each affected weekday as an explicit holiday. If you instead need business days between arbitrary dates or need to add a duration to a date, use a range-counting or workday-addition capability.