United Kingdom calculator
Window Replacement Cost Calculator
Estimate the cost to replace your windows in the UK. Adjust the number of windows, their size, frame and glazing, and whether you choose full-frame or insert replacement to see an itemised low–high range for your project.
How this calculator is built
Unit costs with sources
This model cites 3 sources for its line-item cost and regional labour inputs.
Regional labour adjustment
The region table applies local labour indexes only to labour-heavy line items.
Published methodology
The methodology page lists the formula, size drivers, labour model, and source links.
How this estimate is calculated
The model prices 5 project line items from published cost inputs. Quantities are driven by the number of windows, their size and style, frame and glazing, and whether they are full-frame or insert replacements. The selected scope and finish adjust those inputs, then the regional index changes only each line's labour share; material prices remain national.
The itemised midpoint is shown as a ±20% planning range. It is not a contractor quote: access, design choices, permits, availability, and site conditions can move the final price.
VAT
The calculator applies the configured standard UK VAT rate of 20% to its renovation estimate and shows the VAT-inclusive total. Some projects or properties can qualify for different treatment, so confirm the rate and any exemptions on each contractor quote.
How firm these costs are
The national renovation model is assembled from the public cost guides cited for its individual inputs, then calibrated against a cited market range. Individual line prices are planning allocations rather than live quotes; compare the result with itemised quotes from qualified contractors before budgeting.
Estimate your project
Change the default inputs to match your scope. The breakdown updates by line item.
Window Replacement Cost by region: typical ranges
Each range applies that region's labour index to the labour-share line items of the default project; materials stay at national prices. Select a region for its full local breakdown and calculator.
| Region | Typical range | Labour index | Permit |
|---|---|---|---|
| East Midlands | £8,989–£13,483 | 95% | Likely |
| East of England | £8,989–£13,483 | 95% | Likely |
| London | £9,696–£14,544 | 112% | Likely |
| North East | £8,989–£13,483 | 95% | Likely |
| North West | £9,030–£13,546 | 96% | Likely |
| Scotland | £9,197–£13,795 | 100% | Likely |
| South East | £9,363–£14,045 | 104% | Likely |
| South West | £9,654–£14,481 | 111% | Likely |
| Wales | £9,114–£13,670 | 98% | Likely |
| West Midlands | £8,989–£13,483 | 95% | Likely |
| Yorkshire and the Humber | £8,947–£13,421 | 94% | Likely |
Common questions
How much does it cost to replace windows in the UK?
Checkatrade puts the average cost of new double glazing for a typical 3-bed house at £8,000–£15,000, usually for 8–12 windows — roughly £1,000–£1,250 per window installed for standard uPVC casements. Those consumer figures are VAT-inclusive; our calculator works from ex-VAT trade costs and then adds the standard 20% VAT on top, so the headline total is the real bill you pay. Larger bay or bow windows, premium frames, and full-frame replacement push the total higher.
What's the difference between insert and full-frame replacement?
An insert (retrofit) window fits inside the existing frame and is faster and cheaper. Full-frame replacement strips the old frame back to the opening, adding removal and trim labour, and is the right choice when the existing frame is rotten or you're changing the window size. Toggle 'Full-frame replacement' to include that extra labour.
Do I need FENSA or building-control sign-off for new windows?
In England and Wales replacement windows must meet Building Regulations (energy efficiency and, on certain windows, fire escape and ventilation). Most installers self-certify through a competent-person scheme such as FENSA or CERTASS, which avoids a separate building-control application. Scotland operates a separate building-standards regime where like-for-like replacement is often exempt — check with your local council.