Working Days Calculator

What is a working days calculator?

A working days calculator tells you how many business days fall between two dates. Unlike a plain day count, it ignores the days you do not work — by default the weekend, Saturday and Sunday — and counts only the days a typical office, school or service would be open. You can also remove public holidays and company closures, so the figure reflects the days when work actually happens.

This matters because calendar days and working days rarely match. A two-week span on the calendar is fourteen days, but only ten of them are usually working days. When you plan a project, quote a delivery window or count notice periods, the working-day figure is the honest one.

When you need working days

Project planning and deadlines

Most schedules are expressed in business days: “ready in five working days,” “two weeks’ notice,” “settlement within ten business days.” Converting these promises into real calendar dates — and back again — is exactly what a working-day count is for.

Payroll, leave and billing

Salaries, paid leave and many service contracts are measured in working days. Counting them by hand is error-prone once a span crosses weekends and holidays, so an automatic count keeps timesheets and invoices consistent.

How does the calculator work?

You provide a start date and an end date. The calculator then steps through every calendar day in the range and keeps only the working ones:

• Working days is the count of days that are not weekends and not listed holidays.
• Total days is the plain number of calendar days in the range.
• Weekend (non-working) days is the difference between the two, i.e. the days that were skipped.

Three options shape the count:

• Work week — Monday–Friday (the default) treats Saturday and Sunday as non-working; Monday–Saturday counts Saturdays as working days and only skips Sundays.
• Include end date — when off, the range is half-open and the end date is not counted; when on, the end date is counted too (if it is itself a working day).
• Holidays — an optional list of dates (ISO YYYY-MM-DD, separated by commas). Each holiday that lands on a working day inside the range is subtracted once; holidays that fall on a weekend have no effect, because that day was already non-working.

The order of the two dates does not matter — the calculator always uses the absolute span — and a missing or invalid date produces no result.

Formula

Let the start date be $D_s$ and the end date be $D_e$. Counting through the range, a day $d$ is a working day when it is neither a weekend day nor a holiday. The working-day count is the sum of an indicator over every day in the range:

$W = \sum_{d \in [D_s,\, D_e)} \mathbb{1}\!\left[\,\text{weekday}(d) \notin \{\text{Sat}, \text{Sun}\} \;\wedge\; d \notin H\,\right]$

where $H$ is the set of listed holidays and $\mathbb{1}[\cdot]$ is $1$ when the condition holds and $0$ otherwise. When the end date is included, the upper bound becomes the closed interval $[D_s,\, D_e]$.

Equivalently, working days are total days minus the days you skip:

$W = T - E - V$

where $T$ is the total number of calendar days, $E$ is the number of weekend days in the range, and $V$ is the number of holidays that fell on an otherwise-working day.

Examples

1. Example 1 — two calendar weeks, end excluded.

   • Start date: January 1, 2024 (a Monday)
   • End date: January 15, 2024 (a Monday)
   • Total days: $14$, Weekend days: $4$
   • Working days: $10$

2. Example 2 — the same span with the end date included.

   • Start date: January 1, 2024
   • End date: January 15, 2024, counted
   • Working days: $11$ (the final Monday is added)

3. Example 3 — a full month (the classic August case).

   • Start date: August 1, 2022 (a Monday)
   • End date: August 31, 2022 (a Wednesday), included
   • Total days: $31$, Weekend days: $8$
   • Working days: $31 - 8 = 23$

4. Example 4 — subtracting a holiday.

   • Start date: January 1, 2024, End date: January 15, 2024, included
   • Holiday: January 1, 2024 (New Year’s Day, a Monday)
   • Working days: $11 - 1 = 10$

Notes

• Holidays vary by country, region and employer, so the calculator does not assume any — you list the ones that apply to you.
• A holiday that already falls on a weekend changes nothing, because that day was never counted as a working day.
• Switching to a six-day work week counts Saturdays as working days; Sunday is always treated as non-working.
• The count is based on calendar dates and is independent of time zones.

FAQs

Are weekends ever counted as working days?

Not in the default Monday–Friday mode. If your week runs Monday to Saturday, switch the work-week option and Saturdays will be counted while only Sundays are skipped.

Should I include the end date?

It depends on the convention you are following. “Five working days from today” usually counts the days after today, so the end date is excluded; a date range that names both endpoints as work days should include it. The toggle lets you match either rule.

How do I add several holidays?

List them as ISO dates separated by commas, for example 2024-12-25, 2024-12-26. Each one that lands on a working day inside the range is removed from the total.

Does the order of the dates matter?

No. The calculator always uses the absolute span between the two dates, so swapping start and end gives the same number of working days.