Date Calculator — Business Days & Duration
Two calculators on one page: count working days between dates with weekends (and optionally US federal holidays) excluded, or measure the exact calendar duration between dates and shift a date by any number of days.
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Try Moda free →How business days are counted
The count starts the day after your start date and runs through the end date, skipping Saturdays and Sundays. That fence-post convention matches how deadlines work in practice: “5 business days from Monday” means Tuesday through the following Monday, and a start and end on the same day is 0 days, not 1. It also means Friday to Monday is exactly 1 business day — the weekend in between contributes nothing. If you need the other convention (counting the start date itself), add 1 when the start date falls on a weekday.
Which US holidays the toggle removes
The holiday toggle removes the eleven US federal holidays: New Year’s Day, Martin Luther King Jr. Day, Presidents’ Day, Memorial Day, Juneteenth, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving, and Christmas. Fixed-date holidays follow the federal observance rule — when July 4 lands on a Saturday the preceding Friday is skipped instead, and a Sunday holiday shifts to Monday. State holidays, company closures, and non-US calendars are not included, so treat the result as a federal-calendar baseline.
Why “months between dates” has no single right answer
January 31 to February 28 is 28 days — is that one month? Calendar months vary from 28 to 31 days, so this calculator reports the duration several ways at once: total days (unambiguous), full weeks plus leftover days, and a years/months/days breakdown that walks real calendar months — a month from January 31 lands on the last day of February, and the leftover days are counted from there, so January 31 to February 28 reads as exactly one month. Leap years fall out naturally: February 28, 2024 to March 1, 2024 is 2 days because 2024 has a February 29, while the same dates in 2025 are 1 day apart.
Adding days is calendar math, not clock math
The add/subtract control moves in whole calendar days, so the result is immune to daylight saving time — 30 days after March 1 is March 31 even though one of those days was 23 hours long. It counts every day, weekends included; to land on a working day, run the result back through the business-days tab. Negative numbers subtract, which answers questions like “what date was 90 days ago” for retention windows and lookback periods.
Frequently asked questions
Is the start date included in the business-day count?
No. Counting starts the day after the start date and includes the end date, so Monday to Tuesday is 1 business day and a date to itself is 0. This matches the common “N business days from today” deadline convention. If your context counts the start date too, add 1 when the start falls on a weekday.
Which holidays does the calculator skip?
With the toggle on, it skips the eleven US federal holidays on their observed dates — including shifted observances when a fixed holiday falls on a weekend. It does not know state holidays, stock-market closures, or your company’s calendar, and with the toggle off it skips only weekends.
How does the calculator handle leap years?
All day counting runs on real calendar dates, so February 29 is counted in leap years and absent otherwise. A duration spanning February 2024 is one day longer than the same-looking span in 2025, and adding 365 days to a date in a leap year can land one calendar day earlier than adding “a year”.
Why do I get a different month count than another calculator?
Month arithmetic has competing conventions because months differ in length. This tool walks actual calendar months and reports leftover days separately — some other calculators approximate a month as 30 days or 30.44 days, which drifts on long spans. When precision matters, use the total-days figure; it has no convention problem.
Does daylight saving time affect the results?
No. Every calculation runs on whole calendar dates rather than clock times, so the 23-hour and 25-hour days around DST transitions still count as exactly one day each.