The price of an aluminium window depends on seven factors: size, how many sections open, the glass, the frame system, the colour, energy-compliance requirements and installation. Size has the biggest effect. At Inso, size alone takes a standard window from R860 (600 x 600 mm) to R5,980 (2,400 x 1,800 mm), before upgrades such as double glazing or custom colours.
Understanding these factors helps you compare quotes fairly and see where extra money actually buys better performance. For the full list of prices by size, see our aluminium window price guide. Get your instant quote.
Table of Contents
Aluminium Window Cost Factors at a Glance
Cost factorImpact on priceExample from Inso’s price listSizeHighA 2,400 x 1,800 mm window costs about six times as much as a 600 x 600 mm windowOpening sectionsMediumAt 1,200 x 1,200 mm, two opening sashes cost R2,220 and one costs R1,865Glass typeMedium to highAll 1,800 mm-high windows include laminated safety glass as standardFrame systemMediumStandard Comfort 30.5 range, U-values 6.00–6.28 W/m²KFrame colourLow to mediumStandard price list is in matt charcoal,SANS 10400 XA complianceVariesMay require upgraded glazing, depending on your climate zone and glass areaInstallationMedium to highQuoted separately, and depends on access and building work
How Does Window Size Affect the Price?
Size is the biggest and most predictable cost factor. A larger window needs more frame, more glass and stronger hardware. In Inso’s price list:
- A 600 x 600 mm top-hung window costs R860.
- A 900 x 1,200 mm top-hung window costs R1,528, about 78% more.
- A 2,400 x 1,800 mm top-hung window costs R5,471, about six times the price of the smallest.
Both width and height raise the price. For side-hung windows:
- Wider, at 1,200 mm high: R1,294 at 600 mm wide, R1,865 at 1,200 mm and R3,480 at 2,400 mm.
- Taller, at 1,200 mm wide: R1,568 at 900 mm high, R1,865 at 1,200 mm, R2,320 at 1,500 mm and R3,179 at 1,800 mm.
Are bigger windows better value?
Per square metre, yes. Small windows cost more per square metre because the frame and hardware make up a bigger share of the price.
WindowPriceApproximate cost per m²600 x 600 mm top-hungR860R2,4701,500 x 1,500 mm side-hungR2,509R1,130
So one larger window can cost less than two small ones covering the same area.
Do custom sizes cost more?
Standard sizes are the most cost-effective, because they’re already priced and designed. Inso also makes custom sizes, priced to your measurements. See standard aluminium window sizes to check whether your openings match a standard size.
Does the Opening Style Change the Price?
Yes. Every opening sash adds hinges, stays, locks and seals, so the number of sections that open affects the price as much as the style does.
At 1,200 x 1,200 mm, Inso’s top-hung window has two opening sashes and costs R2,220. The side-hung window of the same size has one and costs R1,865.
Neither style is always cheaper. At 1,800 x 1,500 mm, the side-hung window has two opening sashes and costs more (R3,784) than the top-hung version (R3,360). Compare the exact configuration in each quote, not just the window type.
What this means for your budget: only pay for opening sections where you need ventilation. Fixed panes cost less and have no moving seals. See where fixed windows work best.
Browse the options: casement windows · awning (top-hung) windows · sliding windows
How Does Glass Affect the Price?
Glass is often the biggest cost variable after size.
Standard glass: Inso’s standard windows use 4 mm clear float glass. Some of the widest windows use 5 mm float glass for the large fixed pane.
Safety glass: South Africa’s building regulations (SANS 10400-N) require safety glass, which means laminated or toughened glass, in certain positions, such as glass close to floor level and in doors. Inso’s 1,800 mm-high windows include 6.38 mm laminated safety glass as standard, and this is already in their price. Budget for safety glass where it’s required, rather than treating it as an optional extra.
Double glazing: double glazing uses two panes with a sealed cavity between them, which insulates better and reduces noise. It costs more than single glazing, but the extra cost affects only the glass part of the window. So the rand difference is small on a bathroom window and larger on a big living room window.
Double glazing is most worth it in:
- Bedrooms and living areas that you heat or cool
- Rooms facing noisy roads
- Exposed, windy elevations
For more detail, read the ultimate window glazing guide, types of glass and triple glazed windows.
How Much Does the Frame System Add?
Aluminium frames are made from extruded profiles, and heavier or more technical profiles cost more.
Inso’s standard price list uses the Comfort 30.5 system, with U-values between 6.00 and 6.28 W/m²K. Inso also offers other casement profiles for larger spans or higher specifications.
Thermally broken profiles have an insulating barrier between the inside and outside of the frame. They reduce heat transfer through the frame and cost more to make. They matter most in high-specification builds, or where the glass is already upgraded to meet energy requirements.
Read more in aluminium window frames.
Does the Frame Colour Affect the Price?
It can. Inso’s standard price list is in matt charcoal, and the company offers white, black, bronze, grey and other finishes.
A good powder coat isn’t just about looks: it protects the aluminium from UV damage, corrosion and coastal salt air. In harsh coastal environments, a higher-specification coating is a worthwhile extra.
See aluminium finishes, aluminium window colours and styles and Inso’s charcoal aluminium windows.
How Does SANS 10400 XA Affect the Price?
SANS 10400 XA is South Africa’s energy efficiency standard for buildings. It sets limits on heat gain and loss through windows and doors, based on your climate zone and how much of the building is glazed. New builds and extensions generally need to comply.
Depending on your design, meeting the standard may mean:
- Upgrading to double glazing
- Using low-emissivity (Low-E) glass
- Choosing a better-performing frame
- Reducing the total glazed area
Each option changes the price differently. Your architect or energy assessor will confirm what applies to your project.
Inso is a SANS 10400 XA compliant manufacturer, so it can specify windows that meet your project’s requirements. Read more in the role of fenestration in reducing heat loss.
What Does Installation Add to the Total Cost?
Installation is quoted separately from the window price, and the cost depends on the job:
Lower cost:
- Replacing a window in an existing opening with good access and a clean reveal
Higher cost:
- New openings that need a lintel, brickwork, plaster and sealing
- Upper-floor windows or restricted access
- Replacing old steel or timber frames, which may need repairs to the opening
Good installation also protects your investment. A window that’s installed badly can leak or draught, however good the product is. See our aluminium window installation guide and Inso’s window replacement service.
How to Keep Costs Down Without Cutting Quality
- Use standard sizes where your design allows. They’re already priced and designed.
- Choose larger windows over several small ones. They cost less per square metre.
- Only make sections open where you need airflow. Fixed panes cost less.
- Use double glazing where it pays off. Bedrooms, living areas and noisy or exposed walls benefit most.
- Don’t cut corners on installation. Fixing a poor installation later costs more.
How to Get an Exact Price
Now you know what drives the price. The quickest way to price your own windows is Inso’s instant quote calculator: enter your sizes, glass and colour, and your quote goes straight to your inbox.
Pricing doors for the same project? See our aluminium door price guide.
Frequently Asked Questions
What is the biggest factor in aluminium window prices?
Size. At Inso, a 600 x 600 mm top-hung window costs R860, while a 2,400 x 1,800 mm top-hung window costs R5,471. After size, the biggest factors are the number of opening sections and the type of glass.
Why are aluminium windows more expensive than some alternatives?
Aluminium can cost more upfront than some uPVC or timber windows. In return, it’s strong enough for slim frames and large panes, doesn’t warp or rot, and needs little maintenance. See uPVC vs aluminium windows for a full comparison.
Are larger aluminium windows cheaper per square metre?
Yes. In Inso’s price list, a 600 x 600 mm window works out to about R2,470 per m², while a 1,500 x 1,500 mm window works out to about R1,130 per m².
Does double glazing always cost much more?
No. The extra cost applies to the glass, not the whole window. On a small window the difference is modest, and on large windows it’s bigger.
Is safety glass included in the price?
Inso’s 1,800 mm-high windows include 6.38 mm laminated safety glass as standard, and it’s already in the listed price.
Do I need SANS 10400 XA compliant windows?
New builds and extensions generally need to comply with SANS 10400 XA. What that means for your windows depends on your climate zone and glazed area, so your architect or energy assessor will confirm the requirements.
