Double Glazing Calculator

Calculate double glazing costs for windows and doors. U-value comparisons, argon fill pricing, Low-E coating options, and warm-edge spacer upgrades for accurate DGU quotes.

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Estimate Your Double Glazed Unit

Preview pricing only. Full calculator adds glass thickness (4mm, 6mm, 8mm), cavity depth (12, 16, 20mm), gas fill (air, argon, krypton), Low-E coating position, and warm-edge spacer selection.

Accurate Double Glazing Pricing

Every variable that moves a DGU price — built into one calculator.

1

U-Value Driven Pricing

Enter target Uw value and the calculator recommends glass configurations that hit it — 4-12-4 argon Low-E delivers Ug 1.1, 4-16-4 delivers Ug 1.0, 4-18-4 krypton delivers Ug 0.7. Pricing updates as spec improves.

2

Warm-Edge vs Aluminium Spacers

Aluminium spacer (cheapest, Uw penalty of 0.1-0.2), Swisspacer (mid-range, standard upgrade), Super Spacer (premium, best thermal performance). Each adds different cost per linear metre of glass edge — and the calculator factors perimeter automatically.

3

Low-E Coating Position

Soft-coat Low-E on position #3 (inner pane, outer surface) is standard. Position #2 increases solar gain — useful for cold climates. The calculator handles both, including stacking tolerances and warranty considerations.

4

Gas Fill & Retention Rate

Air (free), argon (~€1-2/m² uplift), krypton (~€15-25/m² uplift). Factor in gas retention over time — quality spacer systems retain 90%+ of gas fill after 10 years; poor systems drop to 70-80%. Factored into lifetime value calculations.

Frequently Asked Questions

What's the difference between 4-12-4 and 4-16-4 double glazing?
The middle number is cavity depth in mm. 4-16-4 has a 16mm cavity vs 12mm — wider cavities generally improve thermal performance up to about 18mm, after which convection losses start to offset the gain. For argon-filled Low-E units, 16mm is the sweet spot for most applications.
How much does double glazing actually save?
Replacing single-glazed windows with 4-16-4 argon Low-E DGUs typically cuts window heat loss by 70-80%. For a typical UK semi-detached house with 10 windows, that's roughly £150-250/year in heating savings — modest per year but meaningful over the 25-30 year life of the window.
Is 4-20-4 better than 4-16-4?
For air-filled units, yes — a larger cavity reduces conduction. For argon-filled units, the improvement is marginal above 16mm because convection within the cavity increases. Krypton-filled units can go to 12mm and still match argon-filled 16mm performance — useful for slim-profile windows in listed buildings.
Does the calculator handle acoustic glazing?
Yes. Asymmetric glass combinations like 6.4-16-4 (laminated 6.4mm + standard 4mm) improve acoustic performance by breaking up resonant frequencies. The calculator covers acoustic PVB interlayer pricing and calculates expected Rw values for urban and high-noise applications.

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Price Double Glazing With Confidence

Every variable. Every configuration. Every pricing scenario. Doorwin has them built in.

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