How to count working days between two dates, and add working days to a date

A working day is a calendar day that is neither a weekend day nor a holiday you observe. That sounds obvious until you count across a month by hand, or across a country boundary: the same two dates give a different answer in Riyadh and in London, because Saudi Arabia's weekend is Friday and Saturday while Britain's is Saturday and Sunday. The free Cubbbix Working Days Calculator counts it for you, and it also runs the count the other way, adding a number of working days to a start date to find a deadline.

Two settings decide most answers, and both are easy to get wrong. The first is the weekend preset: pick the one that matches the organisation you are counting for, not the country you happen to live in, because private employers in the Gulf often keep a different week from the government. The second is whether the end date counts. Days between 1 November and 10 November usually means 9 days, but a leave form asking for days from 1 to 10 November inclusive means 10. The tool asks you to pick, so the answer matches the form you are filling in.

Figure 1: The weekend preset and the end-date setting decide the count. Set both before you trust the number.

Weekends are not universal

Saudi Arabia moved from a Thursday and Friday weekend to Friday and Saturday in June 2013, with a Sunday to Thursday working week. The UAE federal government moved the other way in January 2022, to a Saturday and Sunday weekend with a four-and-a-half-day week, while Sharjah government staff work Monday to Thursday and take Friday, Saturday and Sunday off. A count built on the wrong preset is wrong by two days a week, which is why the preset sits at the top of the page and not buried in a footnote.

Holidays are typed in, not built in, for a similar reason. A built-in list would go stale every year and would still be wrong for half its users: Islamic holidays move about 11 days earlier each Gregorian year, national days differ by country, and some employers observe days others do not. Typing your own list takes a minute, and it is the only way the count can be right for your case. A count without your holidays is a working-week count, not a leave calculation, and the page says so.

Figure 2: The same week counts differently in Riyadh and London. The preset is the whole difference.

Adding working days finds a deadline

The second mode answers the question project plans and notice periods actually ask: given a start date and a deadline measured in working days, what calendar date is that? Adding 10 working days to a Monday lands on the Friday of the following week, not 10 calendar days later, and a holiday in between pushes it one day further. The tool steps forward one calendar day at a time, skipping weekend days and your listed holidays, until it has counted the number you asked for, so adding 1 working day to a Friday lands on the next working day, not on the Friday itself.

Figure 3: Adding working days steps over weekends and holidays. A calendar-day count would land two days early.

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