Construction cost calculator for new homes & renovations
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Caveat lector! (Reader beware!)
This residential building cost calculator only gives a rough preliminary estimate (similar to the "back-of-an-envelope" estimates used by many building professionals to get a rough idea of the cost before any work begins).
For accurate construction costs you will require detailed construction plans and the services of a quantity surveyor or licensed builder.
The cost of renovations are often impossible to estimate (due to unseen structural issues in the building, etc.)
If you speak to a few building professionals in your area you should be able to get reasonable per-square-metre costs for your own location and requirements. The assumptions shown below are based on the author's personal experience building custom homes in NSW - they do not apply to kit homes or project homes, which are much cheaper to build (and currently cost approximatly $900 - $1200 per square metre).
Assumptions
Cost assumptions built into by our construction cost calculator are as follows (but you can easily change them):
- A custom designed house on an excellent site using basic finishes will cost $1500/square-metre. (Click the "Start Calculator" button to find a more accurate per-square-metre value for your location.)
- A custom designed house on an excellent site using standard finishes will cost $1700/square-metre.
- A custom designed house on an excellent site using luxury finishes will cost at least $1900/square-metre.
- If the site is "good", but not excellent, add 7% to the cost.
- If the site is "difficult", add at least 20% to the cost.
- Renovations cost twice as much, per square metre, as new home construction or extensions.
Where to find costing data
- Building Express Calculator: Use this calculator (created by Reed Construction Data) in combination with ours for comparison purposes, or to get a per-square-metre cost for your own area (that you can then use in conjunction with our construction cost calculator).
- BMT & Assoc Quantity Surveyors: Construction costs per square metre - Sydney.
Further Reading
You may find it beneficial to read the following related home design and building articles: