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What is a Working Days Calculator?

A Working Days Calculator is a digital tool designed specifically to calculate the number of working days between two dates, excluding weekends (Saturday and Sunday) and public holidays. This calculator is essential for HR professionals, employees, civil servants, and freelancers who need to calculate project duration, leave applications, or salary calculations based on effective working days. This calculator has two main features: first, the "Calculate Working Days" feature that counts how many work days between a start date and end date. Second, the "Add Working Days" feature that calculates what date it will be after adding a specific number of work days.

Working Days Calculation

Working Days = Total Days - (Weekends + Public Holidays)

Variables:

  • Working DaysWorking Days
    Number of effective working days between two dates(e.g.: 20 working days in a month)
    đź’ˇ Calculating project duration or leave application
  • Total DaysTotal Days
    Total number of calendar days between two dates (inclusive)(e.g.: From January 1 - January 31 = 31 days)
    đź’ˇ Initial calculation basis before subtracting weekends
  • Weekend DaysWeekend Days
    Number of Saturday and Sunday days in the range(e.g.: 8 weekend days in a month)
    đź’ˇ Excluding Saturday-Sunday from calculation
  • HolidaysPublic Holidays
    Public holidays falling within the date range(e.g.: Christmas, New Year, Independence Day)
    đź’ˇ Excluding official holidays from working day calculation

How to Use the KalkuLab Working Days Calculator

  1. 1

    Choose Feature

    Select 'Count Working Days' (between two dates) or 'Add Working Days' (add N working days to a date).

  2. 2

    Enter Dates

    For Count: enter start and end dates. For Add: enter start date and number of working days to add.

  3. 3

    Adjust Settings (Optional)

    Choose work calendar type (Monday–Friday or Monday–Saturday) and check exclude national holidays if needed.

  4. 4

    Click Calculate

    Press Calculate to process instantly with full breakdown.

  5. 5

    View Results and Details

    Results show working day count, end date (for Add mode), and excluded weekends and holidays.

đź’ˇ Tip:

  • •Use the correct date format (DD/MM/YYYY or pick from calendar)
  • •Ensure end date is after start date for accurate results
  • •Check 'Include today' if the first day should count as a working day
  • •Review the current year's national holiday calendar for precision
  • •Use Add Working Days to set realistic project deadlines

Examples

Example 1: Working Days in One Month

Problem:

An employee works from May 1, 2026 to May 31, 2026. How many effective working days if weekends (Sat–Sun) are excluded?

Solution:
  1. 1.Start: May 1, 2026, End: May 31, 2026
  2. 2.Total calendar days: 31
  3. 3.Saturdays and Sundays in May 2026: 10 days (5 Sat + 5 Sun)
  4. 4.Working days = 31 - 10 = 21
  5. 5.If 1 national holiday (e.g., Ascension Day May 29): 21 - 1 = 20 days
Result:20–21 working days

May 2026 has about 20–21 effective working days after weekends and national holidays.

Example 2: Project Deadline (Add Working Days)

Problem:

A project starts May 8, 2026 and needs 15 working days. When is the deadline excluding Sat–Sun?

Solution:
  1. 1.Start: May 8, 2026 (Thursday)
  2. 2.Add 15 working days
  3. 3.If 5-day week: skip weekend May 10–11
  4. 4.Continue counting to 15 working days
  5. 5.Result: around May 28–29, 2026
Result:May 28–29, 2026

The project deadline falls around May 28–29, 2026, depending on whether Saturday counts as a working day.

Example 3: Employee Leave Balance

Problem:

An employee takes leave from June 15, 2026 to June 30, 2026. How many leave days are deducted?

Solution:
  1. 1.Leave start: June 15, End: June 30
  2. 2.Total calendar days: 16 (inclusive)
  3. 3.Weekends in range: 6 days
  4. 4.Working days = 16 - 6 = 10
  5. 5.If June 20 is a holiday (Eid al-Adha): 10 - 1 = 9 days
Result:9–10 leave days

The employee uses 9–10 leave days because weekends and national holidays are not deducted from leave balance.

Example 4: Freelancer Contract Duration

Problem:

A freelancer has a project from July 1, 2026 to July 31, 2026. How many working days must they work?

Solution:
  1. 1.July 2026 has 31 total days
  2. 2.Weekends: about 10 days
  3. 3.National holiday in July: estimated 1 day (Eid al-Fitr)
  4. 4.Working days = 31 - 10 - 1 = 20 days
Result:20 working days

The freelancer must complete deliverables within 20 effective working days by end of July.

Example 5: Daily Wage Payroll Period

Problem:

A company pays daily wages for the 1st–15th of each month. If May 2026 starts on Friday, how many working days are counted?

Solution:
  1. 1.Period: May 1–15, 2026 (15 calendar days)
  2. 2.Weekends: May 3–4 and May 10–11 = 4 days
  3. 3.Working days = 15 - 4 = 11 days
Result:11 working days

Daily wage employees receive pay for 11 working days in the May 1–15, 2026 period.

Frequently Asked Questions

What are effective working days?
Effective working days are weekdays when office or school activity occurs, usually Monday–Friday (5-day week) or Monday–Saturday (6-day week). They exclude weekends (Saturday–Sunday) and national holidays.
How do I calculate working days with a 6-day work week?
With a 6-day week (Monday–Saturday), only Sunday is excluded. Set the calculator to 'Monday–Saturday' for accurate results.
Are national holidays counted as working days?
No. National holidays such as major religious holidays, Christmas, New Year, and other official holidays are not working days. The KalkuLab Working Days Calculator can exclude Indonesian national holidays automatically.
Can I count working days backward?
Yes, you can count backward by entering dates accordingly. However, the Add Working Days feature only supports forward addition (backward is not yet supported).
Does this calculator include collective leave days?
This calculator covers official national holidays. For collective leave (such as extended holiday periods), add them manually in settings if available, or calculate separately.
What if the date range is only one day (start = end)?
If start and end dates are the same, the calculator checks whether that date is a working day (not a weekend or holiday). If yes, result is 1 working day; if not, result is 0.
Can this calculator count school days?
Yes, set working days to Monday–Friday (or Monday–Saturday if school has Saturday activities). Note that school semester breaks are not detected automatically.
Is the KalkuLab working days calculator free?
Yes, it is completely free with no hidden fees. Use it anytime in a browser on smartphone, tablet, or computer without registration.

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References