Business days from the start
US calendar
Landing date
—
Business days—
Calendar days—
Weekend days—
Holidays—
Give it a date and a number of working days and it tells you where that lands, skipping weekends and public holidays as it walks. Enter a negative number to run the same walk backwards. This is the arithmetic that hand-counting on a wall calendar gets wrong, and it gets it wrong worst in December.
Step by step
01Pick the calendar before anything else
US or UK (England & Wales). This is the setting that changes the answer — the same start date and the same number of days land on different dates depending on whose holidays apply.
02Enter the starting date
The count starts from the next working day, not from this one. If the starting date is itself a weekend or a holiday, the walk simply begins at the next day that is neither.
03Enter the number of working days
Positive to go forward to a deadline, negative to go backwards from one. Ten is the most common figure in service agreements and the one most often mis-counted.
04Read the holidays it skipped
Every public holiday inside the walk is listed by name and date. If the result looks further out than you expected, the reason is in that list rather than in the arithmetic.
Worked example
The single worst fortnight in the year to promise anything, worked end to end against the US calendar.
Given
Where ten working days actually lands
start Mon 21 Dec 2026
+14 calendar days Mon 4 Jan 2027
+10 working days Wed 6 Jan 2027
skipped: 4 weekend days x2 = 4 Sat/Sun
Christmas Day, Fri 25 Dec
New Year's Day, Fri 1 Jan
a fortnight is two days short of the
promise. the deadline you quoted has
already passed when the work arrives.Ten working days is sixteen calendar days here, not fourteen. The gap is entirely holidays, and it opens exactly where deadlines cluster — the turn of the year, Easter, and the week of Thanksgiving. An SLA agreed in November and diarised as a fortnight is two days optimistic in the one stretch of the year when there is nobody around to absorb the difference.
Before you diarise the date
Adding days is a walk, not a multiplication
There is no formula that turns N working days into N × 1.4 calendar days, because holidays are not evenly spaced. The only correct method is to step day by day and test each one, which is what happens here and what nobody does reliably by hand.
Backwards is not simply forwards negated
Stepping back ten working days from a deadline and stepping forward ten from the result need not return you to the same date, because the holidays you cross differ in each direction. If a notice period matters, compute it in the direction the rule is written.
Observed dates move, and employers follow them
A US federal holiday on a Saturday is observed the preceding Friday, and one on a Sunday the following Monday — Independence Day 2026 falls on a Saturday and is observed on Friday 3 July. The walk skips the observed day, because that is the day the office is shut.
Easter moves, so spring deadlines move with it
Good Friday and Easter Monday are computed per year rather than fixed. Two identical ten-working-day promises made in March of consecutive years can land on dates a week apart, and neither is an error.
Your company's closures are not in here
Firms shut between Christmas and New Year, add local days, and honour regional holidays no national calendar carries. Treat this as the floor: the real date is this one or later, never earlier.
Everything is computed locally
The holiday calendars ship with the page, so the walk runs offline and no dates are sent anywhere — which matters when the date is a legal deadline or an unannounced launch.
The judgement call
What you are computing decides the direction and the units.
A deadline N working days from today
Positive days
The ordinary reading of a service-level promise, and the case this page exists for.
The last date a notice could be served
Negative days
The same walk in reverse from the deadline, skipping the days that do not count.
A court or filing deadline
Positive days, then check the rule
Court rules often define their own calendar and their own inclusive convention. Use this as a first pass, not as authority.
'Within 30 days' with no qualifier
Calendar days
Unqualified days normally mean calendar days. Count the plain span instead of walking working days.
Rent, interest, or a daily charge
Calendar days
Money does not take the weekend off. Working-day arithmetic will undercount it every time.
A counterparty in another country
Agree the calendar first
Their weekend and their holidays may both differ. This covers US and UK; anything else belongs in the contract.
Reference
FAQ
Enter the starting date and the number of working days. The calculator steps forward one day at a time, skipping Saturdays, Sundays, and the public holidays in the calendar you select, and stops when it has counted that many working days. The date it lands on is the answer.
Yes — enter a negative number. The same walk runs in reverse, which is what you want for working out the last date a notice could have been served, or the date a file had to be with someone for a deadline to be met.
Only when no holiday falls in the range. Ten working days across Christmas or Easter lands three or four calendar days later than a fortnight would, which is precisely when deadlines are missed and precisely when nobody is available to fix it.
No. The count begins on the next working day, which is the ordinary reading of 'ten working days from today' and how notice periods are normally computed. The starting date is shown in the result so the convention is visible rather than assumed.
The ten US holidays widely observed by private employers, or the eight bank holidays for England and Wales, depending on the calendar you select. Company shutdowns and regional days are not included — no public calendar knows about them, so add your own closures on top.
The holiday calendars ship with the page, so the walk runs offline in your browser. No dates are transmitted.
Keep going
Business Days Calculator
The other direction: two dates in, a working-day count out.
Days Between Dates
Every day counted, for anything that accrues daily.
Cron Builder
Schedule a job that should only run on working days.
Time Zone Converter
Check what a deadline hour means for the other party.