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Deadline / Due Date Calculator

Find a due date by counting forward from a start date — either in calendar days (every day counts) or in business days, where only working days count. Business mode follows the WORKDAY convention: the start day itself is not counted, weekends are skipped, and observed US federal holidays are removed by default. The result includes the day of the week.

Calculate

Default result: Jul 9, 2026

Calendar counts every day. Business counts only working days — the start day is not counted, and weekends (and observed holidays) are skipped.

On by default. In business mode, skips observed federal holidays (Sat → Fri, Sun → Mon). Has no effect in calendar mode.

Result

Jul 9, 2026

Due date

Day of week
Thursday
Jul 9, 2026

How to calculate

Pick a start date and the number of days. Choose Business days to count only working days (the start day is not counted), or Calendar days to count every day including weekends. Leave the holiday toggle on to skip observed US federal holidays in business mode. The result updates as you type.

Calendar mode: dueDate = startDate + count calendar days. Business mode (WORKDAY): begin the day AFTER the start date and step forward, counting only Monday–Friday dates and skipping observed federal holidays (when the toggle is on) until count working days have been counted. The start day is never counted; count = 0 returns the start date unchanged.
Example calculation

Starting from Wednesday, July 1, 2026 and counting 5 business days (the start day is not counted), the next working days are Thursday July 2, then — skipping the observed Independence Day on Friday July 3 and the weekend — Monday July 6, Tuesday July 7, Wednesday July 8, and Thursday July 9. The due date is Thursday, July 9, 2026.

dueDay
July 9, 2026
dayOfWeekName
Thursday

Assumptions

  • In business mode the start day is NOT counted (the WORKDAY convention): from a Monday, 1 business day is the following Tuesday. This is the only convention offered — there is no option to count the start day.
  • Calendar mode counts every day, including weekends and holidays; the holiday toggle has no effect in calendar mode.
  • Weekends are Saturday and Sunday.
  • In business mode, observed US federal holidays are skipped by default. They are computed for each year the count spans and shifted to the observed weekday: a holiday on Saturday is observed the Friday before, and one on Sunday the Monday after.
  • If the start date falls on a weekend or a holiday in business mode, it is not counted; the first counted day is simply the next working day.
  • When you open a shared link the inputs come from the URL first, then from your last-used values saved in this browser, then from the calculator's defaults.

Common mistakes

  • Counting the start day in business mode. The WORKDAY convention excludes it, so 1 business day from a Monday is Tuesday, not Monday.
  • Forgetting that a weekday holiday is skipped in business mode. With the toggle on, the count steps over a date such as the observed Independence Day even though it is a Monday–Friday date, pushing the due date later.
  • Expecting the holiday toggle to change a calendar-mode result. Calendar mode counts every day, so holidays never affect it.

Frequently asked questions

Is the start day counted as day one?

No. In business mode the calculator follows the WORKDAY convention: the start day is not counted, so counting 1 business day from a Monday lands on the following Tuesday. Calendar mode also counts forward from the start date, so a calendar count of 1 lands on the next day.

What is the difference between business and calendar days?

Calendar days count every day, including weekends and holidays. Business days count only working days: weekends are skipped, and observed US federal holidays are skipped by default.

Which holidays are skipped in business mode?

The eleven US federal holidays, shifted to their observed weekday (Saturday holidays move to the Friday before, Sunday holidays to the Monday after). Turn the toggle off to count every weekday and ignore holidays.

What if my start date is a weekend or a holiday?

In business mode the start date is never counted regardless of what day it falls on, so a weekend or holiday start simply means the first counted working day is the next available weekday.

Does daylight saving time affect the result?

No. The calculator counts whole calendar days, so the due date and its day of the week never shift because of a clock change.

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