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Window Glazing Area Calculator

Opening area minus the frame gives net glass; weight follows thickness.

Quick answer

With the default inputs: Opening width 1.5 m · Opening height 1.5 m · Frame width 0.06 m etc.Net glass per unit 1.904 m²

Use your own dimensions ↓

Inputs

pcs
pcs

Result

Net glass per unit
1.904m²
Opening area2.250m²
Glass size1380 × 1380mm
Panes1blocks
Area per pane1.904m²
Total glass area1.90m²
Total glass weight29kg
Profile length (est.)6.00m
How this is worked out

Net glass = (opening width - 2 x frame) x (opening height - 2 x frame). Use the actual profile width: 60-70 mm for thermal-break aluminium, 58-60 mm for uPVC, 50-70 mm for plain aluminium. Glass weighs 2500 kg/m³, so 2.5 kg/m² per mm of thickness - 12.5 for 5 mm, 15 for 6 mm, 20 for 8 mm and 25 kg/m² for 10 mm. That weight drives the handling plan: anything over 50 kg needs two people, over 100 kg needs vacuum lifters or hoisting, and high-level external glazing needs planning ahead. For double glazing add the two glass thicknesses and ignore the gas cavity for weight. Profile length is estimated as opening perimeter plus mullion length, excluding sashes, hardware and gaskets.

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Formula

Glass sizew = opening w − 2×frame; h = opening h − 2×frame
Net glass areaA = w × h
Unit weightq = thickness(mm) × 2.5 (kg/m²)
Total weightW = A × q × count
Profile lengthL = [2×(opening w+h) + mullions×net height] × count
1500×1500 mm opening, 60 mm frame, 6 mm glass, no mullion: glass 1380×1380 mm, 1.904 m² net, 15 kg/m², ~28.6 kg of glass and ~6.00 m of profile.

Glass build-ups: overall thickness, structural thickness and weight per m² (weight = structural thickness × 2.5 kg/m² per mm, the same rule this page uses)

Build-upOverall (mm)Structural (mm)Weight (kg/m²)Typical use
Single 5 mm5.00512.5Small fixed lights, top-hung vents
Single 6 mm6.00615.0Standard sashes, the usual choice
Single 8 mm8.00820.0Large fixed lights, balcony doors
Single 10 mm10.001025.0Floor-to-ceiling glazing
Single 12 mm12.001230.0Oversized fixed panes
5+9A+5 insulating19.001025.0Budget insulating unit
6+12A+6 insulating24.001230.0The mainstream residential unit
8+12A+8 insulating28.001640.0Large-format insulating unit
6+12A+6+12A+6 triple glazed42.001845.0Where acoustics and thermal both matter
5+0.76PVB+5 laminated10.761025.0Fall protection, impact resistance
6+0.76PVB+6 laminated12.761230.0Balustrades, roof lights
8+1.52PVB+8 laminated17.521640.0Large laminated panels, guards

Structural thickness is the plies added together; the air space is excluded because it carries neither weight nor wind load. 6+12A+6 is 24 mm overall but 12 mm structural, hence 30 kg/m². Entering 24 in the thickness field on this page returns 60 kg/m², exactly double. Triple glazing at 6+12A+6+12A+6 is 42 mm overall and 18 mm structural, yet weighs only 45 kg/m² — five more than 8+12A+8. The two extra cavities add depth, not mass; the extra ply adds mass.

Common opening sizes (60 mm frame, single-pane glass weight under three build-ups)

Opening W×H (m)Glass size (mm)Area per pane (m²)Single 6 mm (kg)6+12A+6 (kg)8+12A+8 (kg)
0.9×1.5780×13801.07616.132.343.1
1.2×1.51080×13801.49022.444.759.6
1.5×1.51380×13801.90428.657.176.2
1.8×1.51680×13802.31834.869.692.7
1.5×2.11380×19802.73241.082.0109.3
2.4×1.82280×16803.83057.5114.9153.2
3.0×2.12880×19805.70285.5171.1228.1
3.6×2.43480×22807.934119.0238.0317.4

The net glass size deducts one frame width on all four sides, so it is smaller than the opening; a two-pane window then divides by the pane count (the area is unchanged but it becomes two separate pieces to order). The three weight columns are single 6 mm, 6+12A+6 (structural 12) and 8+12A+8 (structural 16); for any other build-up use area × structural thickness × 2.5. The 3.6 × 2.4 row comes to 119 kg in single 6 mm, which two people cannot lift — at that size you are into insulating units and a hoist.

Basis

FAQ

How do I weigh double glazing?
Count the glass only - the gas or dried air in the cavity is negligible. 5+12A+5 behaves like 10 mm glass at 25 kg/m², and 6+12A+6 like 12 mm at 30 kg/m². The aluminium spacer bar and desiccant add roughly 0.5-1 kg/m²; for exact figures the supplier will quote the actual unit weight.
How much smaller is the glass than the opening?
The difference is the frame ring. For a 1500×1500 opening with 60 mm frame: 2.25 m² opening against 1.904 m² of glass, so glass is 85% of the opening and the frame takes 15%. The narrower the opening and the wider the frame, the bigger that gap - a 600×600 opening with a 70 mm frame can come down to about 62% glass. Ordering glass by opening area will always over-order; order by net area.
For 6+12A+6 insulating glass, what goes in the thickness field?
Enter 12, not 24. The field wants the structural thickness of the glass itself — the plies added together. The air space carries no weight and must be left out. Entering 24 gives 60 kg/m² against a true 30 kg/m², which doubles the load used to size hardware and lifting. Triple glazing 6+12A+6+12A+6 takes 18, and laminated 6+0.76PVB+6 still takes 12, since the interlayer weight is negligible.
How heavy is the glass in one window, and how does that drive the hardware?
Weight = pane area × structural thickness × 2.5. Take a 1.8 × 1.5 m opening with a 60 mm frame: the glass is 1680 × 1380 mm, 2.318 m². That is 34.8 kg in single 6 mm, 69.5 kg in 6+12A+6 and 92.7 kg in 8+12A+8. The same opening varies almost threefold, so hinges, friction stays and restrictors are checked against the glass weight, not the frame size.
Is a thicker air space always better?
No. 12A to 16A is the economic band. Too thin and conduction dominates; too thick and convection inside the cavity picks up, so beyond about 20 mm the thermal gain is small while the frame depth, weight and hardware load all rise. The Low-E coating and argon fill matter more than cavity thickness alone.
What frame width goes in — the profile series number?
Not the series number. A 70 series describes the depth of the frame section, whereas the glass size depends on the sight-line width — how much of the glass edge the frame actually covers, typically 10-20 mm less than the series number. Using 70 mm for a 70 series understates the glass. Get the node detail from the fabricator, or measure the sight size of a finished window and work back.

Cite this page

Use this format in reports, method statements or coursework. The link is permanent.

Building Calculator. Window Glazing Area Calculator. 2026-10-25. https://jianzhujisuan.com/en/window-glazing-area

Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.