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Liquidated damages calculator
Work out your liquidated damages exposure on an Australian construction contract. Enter the LD rate, the delay and any extension of time already granted. You get the capped and uncapped figures, and the working behind them.
What are liquidated damages?
Liquidated damages are a pre-agreed sum the contractor pays the principal for each day the works run past the date for Practical Completion. The rate is fixed in the contract particulars before anyone knows whether the job will actually run late.
The point of an LD clause is certainty. Without one, a principal who suffered delay would have to prove its actual loss item by item: lost rent, holding costs, extended consultant fees, finance charges. With one, both sides know the daily number up front and nobody has to litigate the loss.
That cuts both ways. The contractor gains certainty too: its exposure is capped at a known rate rather than whatever the principal can later prove.
How liquidated damages are calculated
The arithmetic is simple. The judgement is in the inputs.
Delay days = actual date of Practical Completion − (date for Practical Completion + extension of time granted)
LD exposure = delay days × the LD rate, then capped at whatever limit the contract sets.
Worked example. A contract has a date for PC of 30 June, an LD rate of 5,000 dollars per day and a cap of 5 per cent on a 12 million dollar contract sum. The works reach PC on 11 August, 42 days late, and 12 days of EOT have been granted. The compensable delay is 30 days, so exposure is 150,000 dollars, comfortably under the 600,000 dollar cap.
Two inputs decide almost every dispute: how many days of EOT are granted, and whether the contract counts calendar days or business days. Check the particulars before you count anything.
The cap is the input most people forget
Most standard Australian contract forms cap liquidated damages, usually as a percentage of the contract sum. Five per cent is common, though it is negotiated and varies widely.
Spreadsheet calculations routinely miss the cap and overstate exposure, sometimes by a large multiple on a long delay. The calculator above always shows both figures so you can see whether the cap actually bites, and what it saves when it does.
Worth knowing: once the cap is reached, the principal generally cannot recover more for delay under the LD clause. In some contracts reaching the cap is also a trigger for termination rights, so it is a commercial milestone, not just an accounting one.
Liquidated damages are not a penalty
An LD clause is enforceable because it represents a genuine attempt to estimate the loss delay would cause, made at the time the contract was formed. It does not have to be accurate in hindsight. It has to have been reasonable in prospect.
Where the rate is out of all proportion to any conceivable loss, a court may find the clause is a penalty and refuse to enforce it. That is not a good outcome for either side: the principal falls back to proving its actual loss, and the contractor loses the certainty of a known ceiling.
This is fact-specific and worth advice. The calculator gives you the arithmetic, not a view on enforceability.
Extension of time is the other half of the question
Every day of EOT granted moves the date for Practical Completion out by a day, and removes a day of liquidated damages. The two calculations are the same calculation viewed from opposite ends.
Which is why the honest answer to “what are we exposed to?” is usually a range, not a number: worst case if no further EOT is granted, best case if every claimed day is allowed. Enter your undetermined EOT days above and the calculator will show both.
One practical warning. Most EOT entitlements are lost on notice, not on merit. Standard contract forms require written notice within a short window of the delay becoming apparent, and a claim that misses that window can fail however good the underlying entitlement was.
Common questions about liquidated damages
How are liquidated damages calculated in Australia?
What is a typical liquidated damages rate?
Can liquidated damages exceed the cap?
Do liquidated damages apply if the delay was caused by the principal?
Are liquidated damages the same as a penalty?
Where this sits in Plexa
This calculator answers the question once. Plexa’s Finance & Budget module tracks the contract dates, EOT determinations and cost-to-complete on the live project record, so the exposure is always current rather than recalculated in a spreadsheet when someone asks.
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