Construction cost calculator/estimator
New homes, renovations & extensions

About our construction cost calculator...

Our construction cost calculator only gives an estimate of building costs . It is only suitable for use before any detailed plans are made. Note: You will need to adjust the default per-square-metre cost to a value more suitable for your area.

Building and construction industry professionals should consider contacting Cordell Estimating who can provide more accurate cost estimating solutions.

People who are not building industry professionals, and who are looking for acccurate residential construction costs, will require detailed construction plans and the services of a quantity surveyor or a licensed builder.

Also note: The cost of renovations & additions are often impossible to estimate accurately due to unseen structural issues in the building.

The DIY approach: If you speak to a few builders 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 ($900 - $1200 per square metre).

Please note: we now sell a full-featured smartphone version of our construction cost calculator. It allows you to save your results. If you'd like a desktop version that saves results please contact us.

Cost assumptions

Cost assumptions built into by our construction cost calculator are as follows:
(Note: They are easy to change!)

• Renovations, additions or extensions often cost twice as much, per square metre, as the construction of a new house or building (e.g. a detached granny flat). Please note: Some jobs will cost more than double, and a few jobs will cost the lucky owner less than double; it is best to speak to at least one builder or other construction professional to determine what the case will be for your job. You can then make adjustments to the calculator's settings to account for this.
• A custom designed house on an excellent site using basic finishes will have a base cost of $1500/square-metre.
• A custom designed house on an excellent site using standard finishes will cost an extra $300/square-metre ($1800 per square metre).
• A custom designed house on an excellent site using high-end or luxury items such as expensive bathroom or lighting fittings will cost at least $600 extra per square-metre ($2100 per square-metre).
• If the building site is "good", but not excellent, add 7% to the base cost of $1500 (eg. a slightly sloping block of land).
• If the building site is "difficult", add at least 20% to the base cost (eg. a steep block of land, or one that requires extra drainage).
• Outdoor areas such as decks, patios and verandahs cost on average $900/square metre. Use a higher value if the outdoor area will have a roof, or will be high of the ground.
• Garages cost an average of $1200 per square metre. Use a higher value if there are any complications such as a sloping block, poor drainage, etc.

Construction choices

For a complete range of construction materials, suppliers and trades professionals see buildingchoice.com.au. This all-in-one website caters for floor coverings, insulation, doors, bricks and more.

Where you can find costing data

Cordell Estimating has a range of costing solutions to assist you with estimating.

Quantity Surveyors are frequently utilised to price large and small home building projects including renovations. Renovations often get out of control on price, but if you hire a quantity surveyor you have a better chance of sticking to your budget. Denary Quantity Surveying (02 4962 1505) are based on the east coast of NSW but service clients nationwide, providing construction cost estimates and tax depreciation reports.

Home Estimators are an economical option to costing your new home, renovation or large residential development. Home Estimators are Melbourne based but operate Australia-wide. You can call them on 0438 187 885.

Use a quoting service such as ServiceSeeking.com.au - post a job online and various builders quote on it. To date the value for home-construction quotes on Service Seeking has been between $1100 and $1650. Unfortunatly it is not known whether that was for additions & renovations or new homes.

Contact local home builders that have been recommended to you, a builder you have used before or try one of our sponsors:

• For the Perth and all of Western Australia contact the ABN Group of building companies and request indicative per-square-metre costs of a new home with different levels of finishes.
• For the Central Coast, Newcastle and Sydney areas try Gecko Homes. Bruce Louis at Gecko offers an initial consultation services for large renovations, new homes and house and land packages. Their contact number is 0413 77 99 79.

A final note: quoting on a new house or renovation is a time consuming process so please be considerate and only call in a builder to give you a detailed quotation when you are committed and ready to move forward.

Start calculating your construction costs >>

Smartphone construction cost calculator

Builders Buddy is a smartphone construction cost estimator & calculator for new houses, renovations & additions. Builders Buddy gives a preliminary estimate of building costs. It is only suitable for use before any detailed plans are made.

Runs on Android or iPhone

• Get the iPhone version.
• Get the Android version

Further reading

Capital allowances for investment properties	Landscaping & gardening articles
How to keep construction costs down	Make Your Home Warm in Winter & Cool in Summer
Kitchen cost calculator	Bathroom cost calculator
Australian residential architecture styles	Becoming an owner builder
Council requirements and reports.	How to read plans
How to read a quote	Residential structures - the basics
Design tips	How to design your own home
Choosing a fence For your Home	Find a local builder

Sponsors

	Master Builder Les Smith specialises in new homes and major renovations and has successfully completed over 100 projects. Les services the Central Coast (NSW) and Newcastle.
	A&M Flynn Building Andrew Flynn's crew of quality tradesmen specialise in the construction of new homes and the implementation of major renovations. Andrew services Sydney's North Shore and the Central Coast of NSW.
	George Brand Real Estate sells and manages more real estate on the Central Coast than any other real estate agency. Looking for holiday accommodation? George Brand has plenty of great place for you to stay.

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