Business days calculator

How the business days calculator works

The calculator does two jobs. In the first, you pick a start date and an end date and it counts the business days between them: every Monday to Friday in the range, minus the US federal holidays if that box is ticked. It also shows how many calendar days and weekend days the range holds, and lists each holiday it skipped.

In the second, you pick a date and a number, and it adds or subtracts that many business days. This is the one for deadlines: an invoice due in 30 business days, a notice period, a delivery estimate. The start date is never counted, so 1 business day after a Friday is the following Monday.

Should the start date count?

This is where most counts go wrong by one, so the calculator lets you choose:

• Count both dates when you want the working days in a period you will spend working, such as a month, a project or a year. Monday to Friday of one week is 5 business days.
• Don’t count the start date when you are counting how long something takes from a given day, such as “within 10 business days of receipt”. Monday to Friday is then 4 business days. It matches adding days: Monday plus 4 business days is Friday.

If a contract or a rule says how to count, follow its wording. Some exclude the day of the event, some say “inclusive”, and courts and agencies often have their own counting rules.

What counts as a business day

A business day is a day when offices are normally open: Monday to Friday, not counting public holidays. Weekends never count. Which holidays count depends on whose calendar you go by. This calculator uses US federal holidays, the days federal offices close, which many banks and businesses also follow.

Federal holidays are not a rule for private employers. The US Department of Labor notes that the Fair Labor Standards Act does not require payment for time not worked, such as holidays, and that this is a matter of agreement between employer and employee (US Department of Labor, holiday pay). Your company may give more days off, or fewer.

Business days per year, 2025 to 2028

Counting every weekday in the calendar year and taking off the observed federal holidays that fall in it:

2027 is the odd one out. New Year’s Day 2028 falls on a Saturday, so it is observed on Friday, December 31, 2027. That gives 2027 twelve federal days off and 2028 only ten. For the month-by-month picture, see working days in 2027 and how many working days are in a month.

Dates are the days off as published by the US Office of Personnel Management. The law names the February holiday Washington’s Birthday; many calendars call it Presidents’ Day. Inauguration Day, January 20 every four years, is an extra holiday only for federal employees in the Washington, DC area, so the calculator leaves it out. In 2025 it fell on Martin Luther King Jr. Day anyway.

When a holiday falls on a weekend

The eleven federal holidays are set in law, in 5 U.S.C. 6103. Six are tied to a weekday, such as Labor Day on the first Monday in September or Thanksgiving on the fourth Thursday in November, so they always land on a workday. The other five have fixed dates: New Year’s Day, Juneteenth, Independence Day, Veterans Day and Christmas Day. When one of those lands on a weekend, the day off moves:

• Saturday holidays move to the Friday before. For employees with a Monday to Friday week, the law makes the Friday the holiday instead. Christmas Day 2027 is on a Saturday, so Friday, December 24 is the day off.
• Sunday holidays move to the Monday after. This comes from an executive order rather than the statute, as OPM explains. Independence Day 2027 is on a Sunday, so Monday, July 5 is the day off.
• Other work schedules follow their own week. For someone whose regular days off are not Saturday and Sunday, a holiday on one of their days off generally moves to the workday before it.

The calculator uses the observed dates, because those are the days offices are actually closed. A holiday that moves into the previous year, like New Year’s Day 2028, is counted in the year it is observed.

Other countries, states and employers

This page only knows US federal holidays from 2025 to 2028. States and cities add their own days, such as state holidays that federal offices do not close for. Other countries have entirely different holiday calendars, and in some the working week does not run Monday to Friday. Banks, courts and stock exchanges keep their own closing days too. If your calendar is different, untick the federal holidays and subtract your own days off from the result.

Counting the days is one half of planning a period of work. To total the hours you actually put in, use the timesheet calculator.

Written and maintained by the DoneThat team. The counts on this page come from the calculator code, and the holiday dates and rules were last checked against OPM and 5 U.S.C. 6103 on 3 November 2026.

Frequently asked questions