Most projects run on weekdays, not on calendar days. A deadline that falls "10 business days from today" works out to roughly two calendar weeks, but if a federal holiday like Thanksgiving or Independence Day sits in between, the real span is longer. This business days calculator counts only Monday-through-Friday weekdays between two dates, and optionally subtracts US federal holidays, so you can quote timelines accurately instead of guessing.
Unlike a generic date difference calculator, which counts every day on the calendar including Saturday and Sunday, this tool filters out weekends automatically. That makes it the right choice for estimating how many working days you have left before a contract milestone, how many billable days fit in a month, how long a vendor lead time really is, or how many days a contractor at $85 per hour can actually deliver in a six-week window.
How to Use
- Enter the Start Year, Start Month, and Start Day for the first date of your interval. For a one-week task beginning Monday, January 1, 2024, you would type 2024, 1, and 1.
- Enter the End Year, End Month, and End Day for the second date. The count is order-independent: swapping the two dates gives the same number. The span is half-open, so the later date itself is not double-counted, just like
busday_countin NumPy. - Set Exclude Fixed US Holidays to 1 if you want the five fixed-date federal holidays that fall inside your span — New Year's Day (January 1), Juneteenth (June 19), Independence Day (July 4), Veterans Day (November 11), and Christmas (December 25) — removed from the count. Leave it at 0 if you only care about weekends. Floating-date holidays (MLK Day, Presidents Day, Memorial Day, Labor Day, Columbus Day, Thanksgiving) are not individually matched.
- Read the result card. Business Days (Mon–Fri) is the headline number. Below it you will see the Total Calendar Days in the span, how many of those were Weekend Days (Sat–Sun), and how many Fixed Holidays Excluded were subtracted when the holiday toggle is on.
A common mistake is to type the same day for start and end and expect "1" — because the interval is half-open, identical dates correctly return 0 business days. To count a single working day, set start to that Monday and end to the following Tuesday.
How the Count Works
The engine counts every calendar date in the half-open interval [lo, hi) and keeps a date only when its weekday is Monday, Tuesday, Wednesday, Thursday, or Friday. Saturday and Sunday are dropped with a closed-form weekend count that stays exact no matter how long the span is. When holiday exclusion is on, the calculator removes the fixed-date US federal holidays that fall inside the span — New Year's Day (January 1), Juneteenth (June 19), Independence Day (July 4), Veterans Day (November 11), and Christmas Day (December 25) — by computing each holiday's absolute day number and testing whether it lies in [lo, hi). The floating-date holidays (MLK Day, Presidents Day, Memorial Day, Labor Day, Columbus Day, Thanksgiving) are not individually matched, so treat the result as exact for weekends and as an estimate for holidays. For spans longer than about one year, holiday subtraction covers the start and end years only; intermediate-year fixed holidays are not individually removed, so budget a rough extra one to five weekdays per open year. Holidays that already fall on a Saturday or Sunday are counted only once and never double-subtracted against the weekend total.
For a rough mental shortcut, one calendar year contains about 260 to 262 business days, depending on leap year and the weekday of January 1. After subtracting 11 federal holidays, the average number of actual US working days in a year is around 249, or roughly 4.8 working days per week. If you bill clients at $150 per hour for 8 hours, each business day is worth $1,200 — so a timeline estimate that ignores holidays can quietly overcommit you by 4% to 5% of capacity.
Examples
Example 1 — A standard month. Set start to January 1, 2024 and end to February 1, 2024. January 2024 has 31 calendar days, 8 of which are weekend days (four Saturdays and four Sundays). The calculator returns 23 business days. With holiday exclusion off, that is the raw Monday–Friday count.
Example 2 — The holiday effect over a full month. Start at January 1, 2024 and end at February 1, 2024. Without holiday exclusion the span has 23 business days. Turn holiday exclusion on, and New Year's Day (Monday, January 1) is detected as a fixed federal holiday inside the window and subtracted, leaving 22 business days. Over a whole year the fixed-date holidays contribute about five weekdays, on top of the floating ones an actual office observes — which is why the average US working year sits near 249 days rather than 260.
Example 3 — A six-week contractor estimate. You need a contractor at $95 per hour, 8 hours per day, for six calendar weeks starting Monday, June 3, 2024. Six weeks is 42 calendar days, 12 of which are weekends, leaving 30 weekdays. Juneteenth (Wednesday, June 19) and Independence Day (Thursday, July 4) both fall inside the window, so with holiday exclusion on the count drops to 28 business days. At 8 hours per day that is 224 billable hours, or about $21,280 at the quoted rate — not the 240 hours a naive 6×5 estimate would suggest.
Example 4 — Identical start and end. Setting both dates to June 15, 2024 returns 0 business days, because the interval contains no days. This is the correct boundary behavior, not a bug.
FAQ
What counts as a business day?
A business day is Monday through Friday, excluding federal holidays when the holiday toggle is on. Saturday and Sunday are never counted, regardless of whether your office happens to be open on a weekend.
Does the calculator include the end date?
No. The interval is half-open, meaning [start, end): the start date is included and the end date is not. This matches the convention used by NumPy's busday_count and by most project-management tools. To count a specific working day, set start to that day and end to the next day.
Which holidays are excluded?
When holiday exclusion is on, the calculator matches the fixed-date US federal holidays that fall inside your span — New Year's Day (Jan 1), Juneteenth (Jun 19), Independence Day (Jul 4), Veterans Day (Nov 11), and Christmas Day (Dec 25). The floating-date holidays (MLK Day, Presidents Day, Memorial Day, Labor Day, Columbus Day, Thanksgiving) are not individually matched, so a span containing only those is treated as having fewer holidays than a real office would. It does not account for state holidays, company holidays, or weather or shutdown closures.
How many business days are in a typical year?
Most calendar years have between 260 and 262 weekdays. After subtracting 11 federal holidays, the average number of actual US working days is around 249 per year, or about 20.8 working days per month. Leap years add one extra day but only shift the count by a small amount.
What if my start date falls on a weekend?
The calculator simply skips the weekend days. If your start is Saturday, March 2, 2024 and your end is Saturday, March 9, 2024, the counted weekdays are March 4 through March 8, giving 5 business days — the same as any Monday-to-Monday week.
Is this the same as a date difference calculator?
No. A date difference calculator counts every calendar day, including weekends. This tool counts only Monday–Friday weekdays, optionally minus holidays. Use this one for project timelines, payroll, billing, and vendor lead times; use the plain date difference tool for age, tenure, or elapsed-time questions.
Disclaimer
This business days calculator is provided for informational purposes only and does not constitute legal, payroll, tax, or project-management advice. Business-day counts depend on your company's holiday calendar, your location, and any special closures; federal holidays listed here reflect the standard US schedule and may not match your organization. Always confirm deadlines and billing days directly with your client, payroll provider, or project manager before making financial commitments.