Building Costing Calculator

Make a quick check of your building budget!

BETA Version 6.0 - Still under development

Updated 1 March 2023 - Rates / costs updated

Please NOTE: There has been a large and unusual spike in building prices during 2021/2022. Please note that we have updated this calculator as a consequence of market price changes. Where pricing is critical, please engage a Quantity Surveyor of get a builders price.
This calculator is for initial feasibility and concept estimates only.

5 Easy Steps

Our costing calculator lets you quickly estimate your likely build across 9 different 'quality levels' of design & construction.

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Step 1

What is your build type?


Measure your plan ...

We have an interactive form that helps you calculate your gross floor area.
Just provide us with the widths and depths of different rooms,
and we will provide the total areas plus the allowances.
Click here to calculate your gross floor area.
Measure all internal floor areas (to the outside of the external walls), including garages.

Do not include carports.
Measure all external built areas like carports, decks, verandas, terraces, balconies, covered areas.

Do not include driveways and paths.
Measure uncovered driveways, gutter crossings & simple paths.

Do not include landscaping.
Measure full extend of pool enclosure that is hard surface or water.

Do not include landscaping.

Step 2

Initial siteworks ...



Only count demolition that is not within a New or Renovated (Internal or external) area (but not driveways or paving).

This is a way of picking up work that falls outside the area of general works.

Measure the area of footprint affected

Add in additional site options like cabanas, sheds etc.

cubic m

cubic m

Measure the area of footprint affected and multiply by the average depth of excavation = volume.

Step 3

Your fit-out items ...

Notes on internal items
The number and type of internal fit-out items can be a major in the cost of a project.

Your building cost will be significantly more if you have many ensuite bathrooms or lots of internal joinery.

The budget cost of these items is adjusted by the Quality scale in Step 4, and the allowance is show in the Summary.

m length

m length

m length

m length

Measure in elevation
ie Area of glass plus frame, 2x2m
window = 4 sqm approx.



Note: Internal doors and windows are
covered in floor areas.

Only add windows here when they are not within an area that is New or Renovated (Internal or external) area (but not driveways or paving).

This is a way of picking up individual window additions or replacements that fall outside the general works.

Step 4

Quality of design / materials / details ...

Building costs vary considerably based on the design,
details, materials, finishes, fixtures & accessories.
Project Homes Custom Homes Architectural Homes
- Try our 12 point checklist (Auto Quality Scale)
(select only one)
(select only one)
(select any / all that apply)
(select any / all that apply)
(select any / all that apply)
(select any / all that apply)
(select any / all that apply)
(select any / all that apply)
(select any / all that apply)
(select any / all that apply)
(select any / all that apply)
(select any / all that apply)

Step 5

Other cost factors ...

These can affect the cost of your home.

Notes on slope
Sloping sites can increase the cost of your home dramatically.

This extra cost is because of more complexity in the structure, more stepping of floor levels, stepping of roofs, more excavation & retaining, more steps and stairs, more difficult scaffolding and more site drainage.

Notes on Access
One for the first things builders will look for is site access.

Difficult access will make your build take longer, because it slows down every trade, makes deliveries more difficult & may require the use of hoists, cranes & conveyors.

Notes on bushfire
There are different categories of construction for different BAL (Bushfire Attack Level) ratings, and the higher ratings create a more costly build.

Notes on Marine
A marine environment will require more attention to detail and a much higher spec. for some fixtures, fittings, finishes and accessories.

Galvanised steelwork, fixings & ties will need to be replaced by special paint finishes and or stainless steel.

Claddings & external light might need to be copper or zinc instead of metal or aluminium.

Notes on Market Conditions
The construction industry is cyclic and this will cause building costs to vary.

There are times when builders will put their rates down to get work and busy times when builders rates get much higher.

Notes on Builders
Being an owner builder will typically save you a ‘builders margin’ but it will likely cost elsewhere in the build and your project will usually take longer to complete.

Notes on Contingency
This is an allowance for costs that will occur on your project but that are hard to estimate with a quick costing. It is for unforeseen items, overruns, some amount of changes in the project that result in extra cost.

Our automatic calculation will suggest a contingency sum for your project and this will vary depending up the size, quality level and other factors. You can allocate your own contingency amount using ‘Custom’.
* This is a common rule of thumb for estimating building costs. Our figure for your renovation is calculated from all the inputs provided to produce a more accurate costing than by using square metre rates alone.
* Rate excludes all Demolition, Excavation, Driveways & Paths, Pools and Spas, and all outdoor living areas, decks, patios, balconies, porches, carports.


Here is your cost breakdown ...

Based on the information provided we have
made some assumptions that will help us
determine your building budget
  Low Range   High Range
Preliminaries (see *1 below) $ 0 - $ 0
Building Shell $ 0 - $ 0
Building Fit-out $ 0 - $ 0
External & Siteworks $ 0 - $ 0
Contingency $ 0 - $ 0
Builder's Margin (see *2 below) $ 0 - $ 0
GST 10% $ 0 - $ 0
Total $ 0 - $ 0


Stormwater systems and On-site detention
Complete rewiring & meter board replacement
Sewer pipe replacement, clay to PVC
Building over sewer mains
Tree removal
Asbestos removal
Internal soft furnishings
Blinds and curtains


This cost covers items such as; the builders surveyor for setting out the works, temporary fencing or hoarding, environmental protection such as erosion and sediment control, general site clearing, scaffolding, amenities, site toilets, first aid, required signage, some specialist documentation such as shop drawings, crane-age, hoists & other equipment hire, permits, some councils fees, dilapidation reports, site cleaning & rubbish /debris removal, contract costs and legals, plus insurances.

Builder's Margin

This builders margin covers the builders overhead and profit. Overhead includes expense items such as office costs, accounting, legals, advertising, vehicles, tools, training, professional and business administration costs.

The covering overheads the remaining profit is reward for taking on risk, provides money for new equipment and growing the business, working capital, and importantly is what they dip into to cover mistakes and some unforeseen costs on your project, i.e. underquoting.

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Sending a copy:

When you send a copy of the costing to your email, it will also be emailed to us for information and for improving our services.

Use this code to retrieve this costing for next time:


This costing is aimed at the budgeting stage & is not intended to replace the costing services of a builder or QS (Quantity Surveyor).
Preliminaries $ 0 - $ 0
Building Shell $ 0 - $ 0
Building Fit-out $ 0 - $ 0
External & Siteworks $ 0 - $ 0
Contingency $ 0 - $ 0
Builder's Margin $ 0 - $ 0
GST 10% $ 0 - $ 0
Total $0 - $0

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Email or call 0412 348 575 and speak to our principal Architect about your project.