Construction Shutdown Calculator
Net working days inside a date range after subtracting industry shutdowns.
Written and maintained by Paul Clark, Redmoon Software · Rules last verified
These calculators are for informational purposes only and do not constitute legal, financial, or professional advice.
How the Construction Shutdown Calculator works
The Construction Shutdown Calculator works out how many working days survive inside a date range once an industry close-down is taken out of it. Enter the range you are measuring and the start and end of the shutdown, and it reports the working days before the shutdown, the working days the shutdown consumes, and the net figure that is actually available to the programme.
This is a different question from a plain business-day count, and the difference is that the shutdown is a block rather than a scatter of individual dates. Construction industries in several countries close down as a sector — the Australian and New Zealand Christmas break, the European summer shutdown, the Nordic July close-down — and those windows swallow whole weeks at a time. Entering the block as a range rather than as a dozen custom dates keeps the input honest and, more usefully, lets the tool report the loss as its own line so you can see what the shutdown cost rather than only what remains.
The shutdown is intersected with your date range rather than assumed to sit inside it, so a shutdown that only partially overlaps the range is counted only for its overlapping portion, and one that falls entirely outside it costs nothing. Within the shutdown window only working days are counted as lost, so a close-down that runs across two weekends does not double-count them. Public holidays inside the shutdown are likewise not counted twice. What the tool will not tell you is whether your contract treats the shutdown as an excusable delay or as time you were expected to plan around — that is a contract-administration question, and the two treatments have very different consequences for an extension of time.
Worked example
A programme window runs Monday, 1 June 2026 to Tuesday, 30 June 2026, holding 21 working days under a US calendar and a five-day week — the Juneteenth holiday on Friday 19 June has already come out. A plant shutdown is scheduled from Monday, 8 June to Friday, 12 June. Those five days are all working days inside the range, so the calculator reports 16 net working days, with the 21, the 5 and the 16 shown separately. Move the shutdown to 27 June – 3 July and only the working days up to the 30th are deducted, because the calculator intersects the two ranges rather than subtracting the shutdown wholesale.
Frequently asked questions
What if the shutdown only partly overlaps my date range?
Only the overlapping portion is deducted. The calculator intersects the shutdown window with the range you are measuring, so a close-down that starts before your range or runs past its end costs you only the working days that actually fall inside. A shutdown entirely outside the range costs nothing and the net figure equals the gross.
Are weekends inside the shutdown counted twice?
No. Only working days are counted as lost to the shutdown, so a two-week close-down spanning two weekends deducts ten days, not fourteen. Public holidays inside the shutdown window are treated the same way — they were already excluded from the working-day count, so they are not deducted again. The net figure is arrived at once, not compounded.
Should a shutdown be an extension of time?
That is a contract question this calculator does not answer. Many standard forms treat a known industry shutdown as time the contractor was expected to programme around, which makes it neither excusable nor compensable; others treat a shutdown imposed after award differently. The day arithmetic here is the same either way — take it to the contract to find out who owns the days.
What this calculator does not do
A limitation you know about costs far less than one you find after the deadline. These are the specific things this tool cannot work out for you.
- Shutdown ranges are subtracted as whole non-working days. Partial-crew or reduced-shift operation during a shutdown cannot be expressed.
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