Formula
Contingency ≈ 5–7.5% of construction cost
WhereHigher for older buildings, refurbishments, or complex sites; lower for repeat product on clean greenfield.
Why it matters
Builders price what they can see at tender. Reality always reveals more, especially on basement, services, and facade work. Contingency is the line that absorbs the difference between the tendered scope and what gets built.
Worked example
For the Waterloo scheme with $12.18M of construction cost, a 5% contingency adds $609,000. A 7.5% contingency would add $914,000.
See it in action
Use this term in a real feasibility.
See these numbers in your own feasibility.
No spreadsheets. No setup. Fourteen-day free trial, no credit card.