Dimensions are only the start of the calculation
A buyer sends a 1200 × 1400 mm size to five suppliers and receives five different totals. It is tempting to label one supplier “expensive”, but the outer dimensions only define geometry. Two companies can quote the same size while offering very different technical packages.
Make the specification comparable first. Only then does the price tell you something about purchasing efficiency, production cost, margin and commercial policy. Otherwise, different products are being compared under the same name.
Profile system and reinforcement change both cost and capability
Profile series differ in depth, gasket concept, material content and market position. PVC adds another variable: steel reinforcement. Its geometry, thickness and application rules matter, especially for large units, dark colours and demanding opening configurations.
In aluminium, profile mass, thermal breaks, system connectors and fabrication details can change the cost substantially. The phrase “aluminium window” predicts the price about as well as the word “car” predicts the price of a vehicle.
The insulating glass unit is often the hidden price driver
Double versus triple glazing is only the beginning. Pane thickness, Low-E coatings, argon, laminated or toughened glass, acoustic interlayers, solar-control coatings and warm-edge spacers change both performance and price. Large dimensions may require thicker or safety glass even when the buyer did not explicitly request it.
A professional quotation should show a readable glass build-up. A specification such as 4/16Ar/4 Low-E is far more informative than a generic phrase such as “insulated glass”.
Hardware, colour and opening type are not minor details
A fixed light and a tilt-turn sash of the same size do not cost the same. Hardware adds hinges, stays, locking points, handles, security components and sash-weight limits. Concealed hardware or burglary-resistance packages add further cost.
Colour can affect the profile price, foil or powder-coating surcharge, lead time, reinforcement rules and finishing details. “Anthracite” is therefore not just an aesthetic note at the bottom of the page.
Installation can be a product in its own right
The element price does not describe the cost of a completed project. Removal, disposal, anchors, foam, sealing tapes, subframes, sills, reveals, cranes and difficult access can create major differences. Two suppliers may price the window similarly while including very different scopes of work.
Ask the quotation to state exactly what installation includes and excludes. “Installation included” without a scope leaves too much room for conflicting expectations.
Margin, discount and tax come last
Suppliers have different purchase prices, productivity, overhead, channels and margin policies. One may show list price and discount, another a net price, and a third may display VAT separately. That can make the comparison even harder.
The solution is simple: create a checklist of technical and commercial items and compare like with like. Once the scope is equal, a 30% difference is no longer a mystery — there is either a concrete reason for it or one supplier truly is more expensive.
