Business Day Calculator

Instructions

1. Enter start and end dates for counting, or a start date and integer offset for adding.
2. Use a seven-digit Monday-to-Sunday weekend mask: 1 means nonworking.
3. Enter holiday dates one per line, then calculate.

Understanding your result

With Saturday and Sunday excluded and no holidays, adding one business day to a Friday gives Monday. Adding excludes the starting day; counting includes working endpoints. Enter holidays yourself so the result represents your schedule rather than a generic weekday count.

What to do if you have a problem

If a result differs from your calendar, inspect weekend selections and every holiday date. A reversed counting interval returns a negative count. Adding days cannot work with every weekday marked as a weekend. Check mode and start date before changing an offset to force a preferred result.

What to know before using the result

No holidays are supplied automatically. Count includes working endpoints and reverses sign for reversed intervals. Adding excludes the start; zero returns it unchanged. An all-weekend mask counts zero but cannot add days. Uses real Gregorian weekdays: dates before March 1, 1900 may differ from Excel’s historical leap-year behavior. Count spans are capped at 20,000 calendar days; offsets at ±10,000 business days. WORKDAY.INTL and NETWORKDAYS.INTL require Excel 2010 or later.

These tools work with pasted text or supported CSV files rather than Excel workbook files. CSV exports contain values and do not preserve workbook formatting, formulas or multiple worksheets. Formula builders produce formula text to use in Excel. Data processing runs in the browser tool.

Try an example

Start 2026-10-02, end 2026-10-09, mask 0000011, no holidays: 6 inclusive business days. Add 5: 2026-10-09.

Summary

Apply the count or offset using your own weekend and holiday calendar.