On this page (11)
How to use this calculator#
- Set the start and end date of the rangeBoth are included in the count, which matches how contracts, courier estimates and statutory notice periods are written. A Monday-to-Friday range gives 5, not 4.
- Tick the weekdays you actually workMonday to Friday is the default, but retail rotas often run Tuesday to Saturday, many Gulf-state offices work Sunday to Thursday, and a part-time week may cover only three days. The count and the per-weekday breakdown both adjust.
- Deduct public holidays yourselfHolidays differ by country, state and employer, so they are not removed automatically. Use the tables below for US federal holidays, and check the per-weekday breakdown to confirm the holiday actually falls on a day you counted.
- Read the weekend total as a cross-checkBusiness days plus weekend days should equal the total calendar days in the range. If they do not, one of the dates is not what you meant it to be.
The formula#
Inclusive working-day count
Business days = ⌊Total days ÷ 7⌋ × (working days per week) + (working days among the leftover days), where Total days = (End − Start) + 1
- Start
- First date of the range — counted
- End
- Last date of the range — also counted
- Total days
- Inclusive calendar days: the elapsed difference plus one
- working days per week
- How many weekdays you have ticked, normally 5
- leftover days
- Total days mod 7 — the partial week at the end, checked date by date
- Holidays
- Subtracted separately, and only when the holiday falls on a day you counted as working
The count is inclusive at both ends, which is the convention in contracts and shipping windows and the opposite of a plain date subtraction. Any whole number of weeks contains exactly your working-days-per-week figure, so all the awkwardness lives in the partial week — which is why the same number of calendar days can yield different working-day totals depending on the starting weekday.
How working days are counted#
The count is inclusive of both the start and end date, matching how contracts and shipping estimates describe a working-day window. Every date in the range is checked against your selected weekdays and counted if it matches. From Monday 5 April to Friday 9 April 2027 there are 5 business days, not 4, because both bookends are working days.
A full seven-day week always contains exactly 5 Monday-to-Friday days, so a 28-day range spanning four whole weeks gives 20 business days. Partial weeks at either end are what make the arithmetic awkward: the same 28-day span starting on a Saturday still holds 20 working days, but starting on a Wednesday it can hold 20 while the weekend days shift position.
Custom working weeks and holidays#
Not everyone works Monday to Friday. Retail and hospitality rotas often run Tuesday to Saturday, many Gulf-state offices work Sunday to Thursday, and part-time schedules may cover only three days. Untick the days you do not work and the count adjusts, along with the per-weekday breakdown showing exactly how many Mondays, Tuesdays and so on the range contains.
Public holidays are not deducted, because they differ by country, state and even employer. If your range covers Thanksgiving week in the US, subtract two days from the result; a UK range spanning Easter loses Good Friday and Easter Monday. Check the weekday breakdown to confirm a holiday actually falls on a day you had counted as working.
Why business-day deadlines differ from calendar days#
A 10 business-day deadline is 14 calendar days when it starts on a Monday, but it stretches to 16 if it starts on a Thursday, because two extra weekend days fall inside the span. This is why ‘within 10 working days’ and ‘within two weeks’ are not interchangeable, and why courier estimates quoted in business days can feel much slower than expected.
Delivery windows, payment terms, statutory notice periods and court filing deadlines are frequently written in working days for exactly this reason — they track effort available rather than time elapsed. Counting the actual weekdays in your specific range is the only reliable way to convert one into the other.
Worked examples#
Counting a four-week block
Monday 5 April 2027 to Friday 30 April 2027.
- Total inclusive calendar days = 30 − 5 + 1 = 26
- 26 ÷ 7 = 3 whole weeks (21 days) with 5 days left over
- 3 whole weeks give 3 × 5 = 15 business days
- The 5 leftover days run Monday 26 to Friday 30 April — all working days, so add 5
- 15 + 5 = 20 business days, and 26 − 20 = 6 weekend days
20 business days and 6 weekend days. No US federal holiday falls in April 2027, so all 20 are working days.
Why a 10-business-day promise is not two weeks
The same ten working days, started on two different weekdays in April 2027.
- Starting Monday 5 April and counting the start day: 5, 6, 7, 8, 9, then 12, 13, 14, 15, 16
- The tenth working day is Friday 16 April — 12 calendar days inclusive
- Starting Thursday 8 April: 8, 9, then 12–16, then 19, 20, 21
- The tenth working day is Wednesday 21 April — 14 calendar days inclusive
12 calendar days or 14, from the same ten-working-day promise. The extra two days are a second weekend pulled inside the window.
Reference tables#
| Month | 2026 weekdays | 2026 after holidays | 2027 weekdays | 2027 after holidays |
|---|---|---|---|---|
| January | 22 | 20 | 21 | 19 |
| February | 20 | 19 | 20 | 19 |
| March | 22 | 22 | 23 | 23 |
| April | 22 | 22 | 22 | 22 |
| May | 21 | 20 | 21 | 20 |
| June | 22 | 21 | 22 | 21 |
| July | 23 | 22 | 22 | 21 |
| August | 21 | 21 | 22 | 22 |
| September | 22 | 21 | 22 | 21 |
| October | 22 | 21 | 21 | 20 |
| November | 21 | 19 | 22 | 20 |
| December | 23 | 22 | 23 | 21 |
| Total | 261 | 250 | 261 | 249 |
December 2027 loses two days rather than one: Christmas Day falls on a Saturday so it is observed on Friday 24 December, and New Year's Day 2028 falls on a Saturday so it is observed on Friday 31 December 2027. Both observed days sit inside 2027.
| Year | Weekdays | Federal holidays observed in the year | Working days |
|---|---|---|---|
| 2024 (leap) | 262 | 11 | 251 |
| 2025 | 261 | 11 | 250 |
| 2026 | 261 | 11 | 250 |
| 2027 | 261 | 12 | 249 |
| 2028 (leap) | 260 | 10 | 250 |
| 2029 | 261 | 11 | 250 |
| 2030 | 261 | 11 | 250 |
A leap year does not automatically have more weekdays — 2028 has 260, fewer than 2027, because 29 February 2028 is a Tuesday and both 1 January and 31 December 2028 fall at the weekend. The holiday column counts observed dates falling inside the year, which is why 2027 shows 12 and 2028 shows 10.
| Holiday | 2026 | 2027 |
|---|---|---|
| New Year's Day | Thu 1 January | Fri 1 January |
| Birthday of Martin Luther King, Jr. | Mon 19 January | Mon 18 January |
| Washington's Birthday | Mon 16 February | Mon 15 February |
| Memorial Day | Mon 25 May | Mon 31 May |
| Juneteenth National Independence Day | Fri 19 June | Sat 19 June (observed Fri 18 June) |
| Independence Day | Sat 4 July (observed Fri 3 July) | Sun 4 July (observed Mon 5 July) |
| Labor Day | Mon 7 September | Mon 6 September |
| Columbus Day | Mon 12 October | Mon 11 October |
| Veterans Day | Wed 11 November | Thu 11 November |
| Thanksgiving Day | Thu 26 November | Thu 25 November |
| Christmas Day | Fri 25 December | Sat 25 December (observed Fri 24 December) |
A federal holiday falling on a Saturday is observed the preceding Friday, and one falling on a Sunday the following Monday. New Year's Day 2028 is a Saturday, so federal offices close on Friday 31 December 2027 — a twelfth observed holiday inside 2027.
Common mistakes#
- Mixing inclusive and exclusive countingSubtracting one date from another gives the exclusive figure, but business-day windows are almost always inclusive. Monday to Friday is 4 elapsed days and 5 business days, and quoting the wrong one is how a delivery promise or a filing deadline slips by a day.
- Forgetting to deduct public holidaysA range covering US Thanksgiving week loses two working days; a UK range spanning Easter loses Good Friday and Easter Monday. On a ten-day window that is a 20% error, and it always runs in the direction of promising sooner than you can deliver.
- Treating 10 business days as two weeksStarting on a Monday it is 12 calendar days; starting on a Thursday it is 14, and a public holiday inside the window stretches it further still. ‘Within 10 working days’ and ‘within two weeks’ are different promises and should never be swapped in a contract.
- Overlooking the weekend-shift rule for observed holidaysA holiday on a Saturday moves to the Friday before, which can pull it into the previous month or even the previous year. That is exactly why 2027 has 12 observed federal holidays and 2028 has only 10, and why per-month working-day tables cannot be derived from the holiday's nominal date.
Frequently asked questions#
Are both the start and end dates counted?
Yes. The range is inclusive, so a Monday-to-Friday range returns 5 business days. This matches how most contracts and shipping windows are written.
Does it exclude public holidays?
No. Holidays vary by country and employer, so subtract them yourself. The per-weekday breakdown helps you check whether a holiday lands on a day you counted.
Can I count a working week that is not Monday to Friday?
Yes. Tick or untick any weekdays to match your schedule — a Sunday-to-Thursday week or a three-day part-time week both work.
How many working days are in a year?
A common year has 260 or 261 Monday-to-Friday days depending on which weekday 1 January falls on; a leap year can reach 262. Public holidays reduce this further.
Key terms#
- Business day
- A day on which normal business is conducted — Monday to Friday in most Western countries, excluding public holidays.
- Working day
- Used interchangeably with business day, though some contracts define it explicitly as a day banks are open in a named city.
- Banking day
- A day on which banks settle payments. Narrower than a business day, since bank holidays can close settlement while offices stay open.
- Observed holiday
- The day a holiday is actually taken when the nominal date falls at a weekend — the Friday before a Saturday, the Monday after a Sunday under US federal rules.
- Day in lieu
- The UK and Commonwealth equivalent: a substitute day off granted when a bank holiday falls on a weekend.
- Clear days
- A legal count excluding both the first and last day of the period, so it runs one or two days longer than an inclusive count of the same length.
- NETWORKDAYS
- The spreadsheet function that counts inclusive working days between two dates, with an optional list of holidays to exclude.
Sources#
- Federal holidays and the in-lieu-of rules — US Office of Personnel Management
- UK bank holidays — GOV.UK
- ISO 8601 date and time format — International Organization for Standardization
Figures last checked .
Put this calculator on your site
Free, no sign-up, and no attribution fee — just keep the credit line that comes with the code. The calculator stays up to date automatically.