Roof Cost Calculator

Roof replacement cost varies depending on the roofing material you choose and how big your roof is. A budget-friendly Colourbond roof starts at $18 per square metre whereas slate tiles could cost up to $500 per square metre. There will also be an additional installation cost of $40 to $120 per hour.

Want to know how much your specific roofing project will cost? Use our handy calculator above to estimate*. Simply enter the total size of your roof (we help you figure that out below), then choose the type of roofing material you want. 

*Cost is indicative for materials only and does not include labour, removal of old materials, or other costs.

How to calculate the cost of a new roof

Having a 'roof over your head' is essential, but trying to figure out roof replacement costs can feel like a head-scratcher. Use our handy roofing calculator above, or keep reading to discover what impacts the cost of roof replacement and to get an idea of how much your new roof will cost.

Step 1: Understand the factors that impact roof replacement cost

Roof replacement cost varies based on several things, including:

• Roof size: Roofing tends to be quoted per square metre. The larger the roof, the more materials and labour will be required, leading to higher expenses
• Roof design: Different roof types, such as flat roofs, pitched roofs, or skillion roofs, all have different installation and material costs. The more complex your roof replacement is, the more expensive it's going to be
• Roof pitch: The pitch or slope of the roof can also impact the amount of labour and materials needed. Steep roof pitch require extra safety precautions and can be more challenging to work on, resulting in higher costs per square metre
• Roofing material: The type of roofing material you choose plays a significant role in determining the cost. Concrete roof tiles, slate roof tiles, terracotta tiles, and metal roofing like colorbond, all have varying prices per square metre. When choosing, don't just think about cost but also durability, aesthetics, and longevity
• Labour costs: The cost of labour, including the expertise and experience of the roofing contractor, will also vary. Highly skilled contractors charge more for their services, but their expertise means you'll get a speedy and quality installation
• Site access: If it's a tricky site to access, or it's a double-story house then you'll also need to consider additional costs like scaffolding

Step 2: Calculate the total square metres for your roof

To figure out your roof size:

1. Measure the length and width: Use a measuring tape to measure the length and width of each section of your roof. For complex roof shapes, break them down into smaller sections and measure them individually
2. Multiply length and width: Multiply the length and width measurements for each section to calculate the area of that section. If you have multiple sections, repeat this step for each section
3. Add up the areas: Add the areas of all sections together to get the total square metre area of your roof

Remember: Be careful! Only trained roofing professionals with the right safety equipment should be working at height. You could use a floor plan of your home to figure out the size, measure internally, or — the best option — contact a professional roof replacement service that offers free measurement during quoting.

Step 3: Estimate the cost of materials

The next step in calculating the total roof replacement cost is to multiply the total square metres of your roof by the cost of the material you plan to choose.

Average roofing materials cost per square metre Australia

Roofing material costs vary significantly from cheap and cheerful Colorbond roofing to luxury terracotta tiled roofing. The costs shown below are indicative.

• A Colorbond roof typically ranges from $18 to $37 per square metre. This is the cheapest roofing material
• Concrete tiles come in at an average of $45 to $65 per square metre
• Steel roofing falls within an average range of $50 to $70 per square metre
• Corrugated metal roofing is in the same price range, averaging $50 to $70 per square metre
• Asphalt shingles have an average cost of $65 per square metre
• Terracotta tiles are a pricier roofing option and will cost between $80 to $110 per square metre
• Clay tiles have an average cost of $100 per square metre
• Timber roofing averages around $160 per square metre
• Solar roofing tiles are some of the most expensive, at $320 per square metre
• Slate tiles are among the higher-end options, with an average cost of $200 to $500 per square metre

Multiply material cost by roof size

While it's always best to consult with an experienced roofing contractor for an accurate estimate, you can get a rough idea using the following method:

• Determine the roof area: Use the square metre area of your roof, which you calculated earlier
• Research average price: Research the average cost per square metre for the specific roofing material you intend to use
• Multiply area and cost: Multiply the square metre area of your roof by the average cost per square metre for the chosen roofing material. This will give you an estimate of the total cost of materials. Or, use our handy calculator above

Step 4: Include other expenses

Remember, there is more than just materials to think about when it comes to re-roofing cost. You should also consider:

• Labour cost: Factor in how much you'll pay roofing specialists for roof installation. Labour can cost anything from $40 to $120 per hour and the time for the job depends on multiple variables including size of the roof, pitch of the roof, and access
• Old roof removal: If you're replacing an old roof, you'll need to factor in removing and disposal of your old roof. If you're replacing an asbestos roof there will be higher feed for labour, removal and disposal
• Extra components or customisation: If there is anything custom or complex, this will impact roof replacement costs

Step 5: Get multiple quotes

To make sure you're getting a fair price, always obtain quotes from multiple reputable roofing contractors. Compare the quotes, taking into account the quality of materials, labour cost, warranties, and the contractor's reputation.

Roof replacement vs. roof repairs 

Deciding between roof replacement and repairs comes down to the extent of the damage and the overall condition of the existing roof. Roof repairs are usually suitable for isolated issues like minor leaks or a few damaged shingles. However, replacement might be the better choice if the roof has sustained extensive damage, is nearing the end of its lifespan, or has a history of recurring problems.

FAQs about roofing cost

How do you calculate the cost of a roof?

To calculate the cost of a roof, multiply the square metre area by the average cost per square metre of your chosen roofing material, factoring in labour and additional expenses.

How much does a roof cost per square metre in Australia?

The cost of a roof per square metre in Australia can vary widely depending on factors like material, location, and complexity, ranging from $80 to $250 per square metre.

How much does a roof cost in Australia?

The total cost of a roof in Australia depends on various factors, including size, material, labour, and additional components, with averages ranging from $10,000 to $30,000 or more.

How do you calculate the square metres of a roof?

To calculate the square metres of a roof, measure the length and width of each section, multiply these measurements for each section, and then add up the areas to get the total square metre area.

When is it necessary to replace a roof?

A roof replacement is necessary when repairs can no longer effectively address underlying issues, often due to severe weather damage, an aging roof, or recurring problems indicating structural issues.