Business days vs calendar days

What is a business day?

A business day is a day when offices are normally open. In US federal use, that means Monday through Friday, minus the federal holidays. Federal law, 5 U.S.C. 6103, names 11 of them: New Year's Day, Martin Luther King Jr. Day, Washington's Birthday, Memorial Day, Juneteenth, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving and Christmas. The Office of Personnel Management (OPM) publishes the dates each year, including the observed dates when a holiday lands on a weekend.

A calendar day is simpler: every day counts, weekends and holidays included. On this site, "30 days" always means calendar days, and day 30 can be a Sunday. When it says "business days" or "working days," you skip the days offices are closed.

This site uses one definition for every business-day number: Monday to Friday, minus federal holidays on their observed dates. It follows the OPM holiday list. It is not the only definition in use, and the rest of this guide covers where others differ.

How do you convert business days to calendar days?

With no holiday in the way, every 5 business days equals 7 calendar days. That holds whatever weekday you start on, because 5 business days always span exactly one weekend. So 10 business days is 14 calendar days, 20 is 28, and 30 is 42. The table above lists the common ones.

Holidays break the pattern by one day each. Count 10 business days from Mon, Nov 23, 2026 and you cross Thanksgiving on Nov 26, so the count ends one day later than it would in a week with no holiday. Count across Christmas and New Year's 2027 and you lose two.

Numbers that are not multiples of 5 depend on the start day. 3 business days from a Monday end on Thursday, 3 calendar days later. 3 business days from a Wednesday end on Monday, 5 calendar days later, because the weekend sits in the middle.

What happens when a holiday falls on a weekend?

Federal holidays have fixed dates or fixed weekdays. When a fixed-date holiday lands on a Saturday or Sunday, OPM moves the day off for federal employees: Saturday holidays to the Friday before, Sunday holidays to the Monday after. That observed day is the one a business-day count skips.

In 2026, Independence Day is a Saturday, so the observed holiday is Fri, Jul 3. In 2027, three holidays move: Juneteenth (Saturday) to Fri, Jun 18; Independence Day (Sunday) to Mon, Jul 5; and Christmas (Saturday) to Fri, Dec 24. New Year's Day 2028 is a Saturday, so it is observed on Fri, Dec 31, 2027, which gives 2027 two New Year's holidays and 249 business days instead of the usual 250.

Do banks count business days the same way?

Not exactly. The Federal Reserve's holiday schedule lists the same holidays, but its rule for Saturdays differs. The schedule says that for holidays falling on a Saturday, Federal Reserve Banks and Branches will be open the preceding Friday. For Sunday holidays, they close on the Monday after, the same as OPM.

So on Fri, Jun 18, 2027 and Fri, Dec 24, 2027, federal offices are closed but Federal Reserve Banks are open. If your deadline depends on a bank transfer, a one-day difference can matter. The business days calculator follows OPM by default; the holiday table above shows where the Federal Reserve differs.

When is a "day" not a business day?

Plenty of rules use calendar days even when the subject sounds like business. The IRS 60-day IRA rollover window in Publication 590-A is stated in days. The federal 120-day wait before a mortgage servicer can start foreclosure, in 12 CFR 1024.41, is stated in days. Rental notice periods in California and New York are stated in days, while Texas uses months. Our "days from today" pages count calendar days and show the business-day date beside them, so you can see both at once.

How should you count your own deadline?

Three questions settle almost every case. Does the rule say days, business days or months? Does day 1 start on the day of the event or the day after? And if the last day lands on a weekend or holiday, does the deadline move? The answers come from the rule itself, not from a calculator. Once you have them, the date calculator and the business days calculator do the arithmetic, and the methodology page explains exactly how they count.