Steel Windows Installation and Replacement Cost Calculator

How this calculator works

This calculator estimates a realistic price range rather than a single figure, because real-world quotes genuinely vary that much. It starts from typical UK supplied-and-fitted price ranges drawn from published 2026 industry cost guides, then multiplies them by the number of units you enter and by adjustment factors for each choice you make below. The result is a low-to-high band that a fair quote is likely to fall within, not a promise of the exact price you will pay.

Genuine steel windows typically cost around to per window supplied and fitted in 2026, making them one of the most expensive window types available. The appeal is the ultra-slim sightline that no other material can quite match, the strength that allows large glass areas, and a lifespan measured in many decades when properly maintained.

Number of steel windows

Enter how many steel windows you are pricing. Genuine steel windows are a specialist product, so projects are often smaller and more targeted than whole-house uPVC replacements, for example a feature elevation, internal screens or replacements on a period building.

Window size

Size is one of the biggest cost drivers for any glazed unit. A larger opening needs more frame material and a bigger, heavier sealed glass unit, and it usually takes longer to fit. The calculator uses three broad size bands based on common UK window dimensions: choosing the small band reduces the typical range by around 20 percent, while the large band increases it by around 40 percent. If your windows vary in size, run the calculator once per size band and add the results together.

Specification level

Two windows that look similar from the street can sit at very different price points. Budget products use simpler profiles, standard hardware and basic glass. Mid-range covers the typical A-rated units most UK installers quote by default. Premium covers high-end systems with upgraded security hardware, better thermal performance, special finishes or designer profiles, and typically adds around 30 percent to the price.

Where you live

Labour rates are not uniform across the UK. Published cost guides consistently show installation prices in London and the South East running roughly 20 to 30 percent above the national average, driven by higher labour costs, travel, parking and congestion charges. The calculator applies an uplift of around 20 percent if you select London and the South East. Product prices themselves are broadly similar nationwide, so the difference mostly reflects fitting costs.

What else affects the price

Steel window pricing is driven by the fabrication, since each window is made to order from hot-rolled or cold-formed steel sections, galvanised and then polyester powder coated. Double glazing slim enough to fit steel profiles costs more than standard units. If the budget will not stretch to genuine steel, heritage steel-look aluminium replicates the aesthetic at roughly half to two thirds of the price and is worth pricing alongside, though purists and some conservation officers will notice the difference. On listed buildings, repair and refurbishment of original steel frames is often preferred, and sometimes required, over replacement.

Planning permission, building regulations and certification

Like-for-like window replacement on most houses does not need planning permission, but listed buildings always require consent and conservation areas often restrict materials and styles on visible elevations, so check with your local planning authority if either applies. Building regulations apply to every replacement window in a dwelling, setting minimum energy performance and safety glazing standards. Installers registered with a competent person scheme, such as FENSA or Certass, can self-certify compliance and issue a certificate after completion; otherwise you must arrange building control sign-off separately. Keep the certificate safe, as buyers’ solicitors routinely ask for it when you sell.