NSW working days calculator

How builders count working days for programs and EOT claims

On a building site, a “day” nearly always means a working day. Most residential contracts in NSW work to the same idea: a working day is a day the trades can actually be on site. Weekends, public holidays and the industry Christmas shutdown don’t count. Saturdays count only if your contract or crew works them. Your contract’s definitions clause decides this, so read it first. The calculator just does the counting.

Programs: durations in working days

When you build a construction program, each task gets a duration in working days. A five-day frame stand that starts Thursday 25 March 2027 doesn’t finish the following Monday. Good Friday, the Easter weekend and Easter Monday all fall in between, so the frame is done on Friday 2 April. This is the “start date is day 1” setting above. It is also how Gantt software, including our Construction Gantt app, draws task bars. Linking tasks this way means one change to a duration pushes every task after it by the right number of working days.

Notices and extension-of-time (EOT) claims

Contract time limits are usually counted from the day after an event. “Within 5 working days of becoming aware of a delay” starts the next day. That is the default setting above and it matches Excel’s WORKDAY function. Using the same Thursday, five working days after 25 March 2027 is Monday 5 April 2027. That is a long way from the 30 March you might assume. Missing an EOT notice deadline can cost you the extension, and sometimes liquidated damages too. Check your contract’s notice periods, and whether they use business days or working days.

To claim an EOT, show how many working days a delay cost. Count the working days lost between two dates, set them against the critical path in your program, and back each day with site diary records: weather, late approvals, owner variations, late information.

NSW public holidays and substitute days

Under the Public Holidays Act 2010 (NSW), some holidays that land on a weekend get an extra weekday. Examples are the Anzac Day additional day on Monday 27 April 2026, and the extra days on 27 and 28 December 2027. Easter Saturday and Easter Sunday are public holidays too, which matters if you work Saturdays.

Christmas shutdown

Many builders and trades close from just before Christmas to around the second week of January. That alone can be ten or more working days. Programs that ignore it end up promising finish dates you can’t meet. Put your actual shutdown dates in the settings above and in your contract’s program.

General information only, not legal advice. Your contract’s definitions and notice clauses decide how days are counted. Check public holiday dates against the NSW Government list before relying on them, especially for 2028.