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Glass & glazing calculators

Specifying glass comes down to four questions: is it thick enough for the load, how much does it weigh, how much heat does it let through, and what goes on the document you send the client. These tools answer them one at a time and hand their results to each other, with the standard cited and the arithmetic visible.

All of them run in your browser. Nothing is uploaded, nothing is stored, and none of them asks you to register.

Cutting optimiserNests your cutting list the way a table actually cuts — strips, guillotine snaps, edge trim and breakout width. Then it does what the free panel nesters get wrong: separates the scrap you bin from the offcut that goes back on the rack.Example 40 units on 4 sheets → 4.1 % scrap, 3.61 m² back on the rackOptimise glass

How they fit together

One answer becomes the next question.

Most sites give you a calculator. This one gives you a route: the design pressure you work out on one page is the load the next page asks for, and the pane it sizes is the pane the third one weighs. No re-typing, and no wondering whether the three of you used the same number.

Size it for the load

Wind on a facade, a barrier under a crowd, a shelf under a point load: stress and deflection with the standard's numbers.

Wind pressure on a facadeDesign pressure from basic wind speed, terrain, height and where the pane sits, to EN 1991-1-4 or ASCE 7. Hands the result straight to the thickness calculator — which is the input it asks you for.Example vb 27 m/s · terrain II · zone A → 2.572 kN/m² design
Thickness & deflection under wind loadChecks bending stress and deflection for a rectangular pane supported on four edges. Monolithic and laminated, annealed through fully tempered, metric and imperial. Also gives you the thinnest standard glass that passes.Example 1200 × 2200 · 10 mm tempered → σ 9.96 · w 3.82 mm
EN 16612 explainedWhat the standard is about and how the thickness calculator applies it: the design strength, the stress and deflection checks, what it asks for, what it assumes and what it leaves out.Example 1200 × 2200 · 10 mm tempered → utilisation 21 %, governed by deflection
Glass load capacityHow much wind or uniform load a pane takes from its size, thickness and glass type: EN 16612 design strength and the deflection.Example 1000 × 1500 · 8 mm float · wind → 2.44 kPa · 6.0 mm deflection
How thick should glass be?The thickness usually fitted for each use, from windows to aquariums, and the calculator that sizes it.
Wind lab: watch a pane bendDrag the pressure, the size and the thickness and watch the glass deflect, with stress and deflection against their limits from the thickness calculator's own formulas. Then take the case to the calculator.Example 1200 × 2200 · 10 mm tempered · 1.20 kN/m² → 21 % of the deflection limit
Glass balustradeStress and deflection of a free-standing barrier under a horizontal line load, at both interlayer bounds — plus the broken-ply check that most calculators quietly skip.Example 1100 mm · 0.74 kN/m · 12+12 → 16.3 mm, 96 % of h/65
Glass pool fenceEqual panels for each run, the gaps, spigots and weight, checked against AS 1926.1 and the US pool code.Example runs of 8000 and 4500 · 1200 high · 12 mm → 9 panels · 18 spigots
Table tops and shelvesHow thick the glass needs to be for a top, a shelf or a screen — checking the spread load and the concentrated one, which is the check that actually decides and the one most guides skip.Example 800 mm shelf · 10 mm · 50 kg point → 19.6 N/mm² vs 7.1 spread
Aquarium glass thicknessFront, ends and bottom of a rimless or braced tank with the water to the brim. The free top edge of a rimless tank decides, and the chart most hobby sites copy leaves it out.Example 120 × 50 × 50 rimless → 12 mm front · 8 mm ends

Weight, heat and sound

What a pane weighs and who lifts it, how much heat a unit lets through, and why two identical panes are bad acoustics.

Glass weightWeight of a pane, a laminated make-up or an insulating unit — total, per unit and per square metre — and what it means for getting it off the van and into the opening.Example 1200 × 2200 · 6 mm → 39.6 kg · 15.0 kg/m² · two people
Glass price calculatorThe price of each pane with your own rates: per m² or square foot, a minimum area per piece, toughening, polished edges per metre and holes, with the weight. Then a budget your customer accepts from a link.Example 1000 × 800 · 8 mm toughened · 4 edges · 2 holes → 66.00 a piece
Glass density and unit weight2500 kg/m³ for float and toughened glass, 24.5 kN/m³ as a unit weight, 2.5 kg per m² per millimetre, with the table by thickness and laminated make-ups.Example 10 mm → 25 kg/m² · 2.32 kg per sq ft
PVB interlayer weightThe interlayer (0.38, 0.76 or 1.52 mm) per m² and the laminated glass it is in, with the density from the makers' data sheets.Example 4 + 4 · 0.76 PVB · 1000 × 2000 → 41.6 kg · 20.81 kg/m²
U-value of an insulating glass unitCentre-pane Ug to EN 673 for double and triple units — air, argon, krypton or xenon, with or without low-E. Splits every cavity into its radiation and gas parts, and tells you the best cavity width for that gas.Example 4-16-4-16-4 argon · two low-E → Ug 0.61 W/(m²·K)
EN 673 explainedHow the Ug of an insulating glass unit is worked out: radiation and gas in each cavity, the standard conditions, which edition the calculator follows and what it leaves out.Example 4-16-4 argon, low-E 0.03 → Ug 1.10
Ug value tableUg of the usual double and triple make-ups with air, argon or krypton and each low-E coating of the calculator, every figure worked out to EN 673 and linked to the calculator with that unit filled in.Example 4-16-4 argon, ε 0.03: Ug 1.1
Glazing configurator: double or triple, layer by layerBuild the unit pane by pane: laminates, the low-E face, cavity width and gas. It draws the section and gives Ug to EN 673, the weight and the make-up to order.Example 4 / 16 Ar / 4, low-E on face 3 → Ug 1.10 · 20.0 kg/m²
Why the two panes must not matchEvery pane goes acoustically transparent at one frequency, and thickness decides which one. Two identical panes fail at the same place, so the unit gets one deep hole instead of two shallow ones — and making them different costs nothing. The coincidence dip, the mass-spring-mass resonance, what an acoustic laminate really does, and why Rw is the wrong number to compare when the window faces a road.Example Rw 40 with Ctr −7 is worse against traffic than Rw 38 with −3
Glass shower door weight and hingesDoor and fixed panel at 6 to 12 mm, how many hinges your hinge's rating allows, and the pull on the top one.Example door 800 × 1950 · 8 mm → 31.2 kg · 9.2 kg on the top hinge
Glass door weightHinged, pivot or sliding, 6 to 19 mm: the weight in kg and lb and what it puts on the hinges, pivots or rollers.Example 900 × 2100 · 10 mm, side-hung → 47.3 kg · two people
Mirror weightRectangular, round or oval, 3 to 8 mm, with its frame: the weight in kg and lb and the load on each hook.Example 600 × 900 · 4 mm · 2 hooks → 5.4 kg · 2.7 kg per hook
Silicone sealant calculatorCartridges for a joint or a corner bead, the depth to use, and the structural silicone bite from the wind.Example 6 × 6 mm joint · 310 ml cartridge → 8.6 m per cartridge · 36 ml/m
Weight and stock size referenceThe handful of numbers that get looked up over and over: what glass weighs per square metre and per full sheet at every thickness, the standard float stock sizes, and the edge trim, breakout and minimum offcut that decide whether a list fits on three sheets or four. One page, made to be printed once and left in the van.Example 2.5 kg/m² per mm — a 6 mm DLF sheet is 108 kg
Glass glossaryThe words of the trade in plain terms, from float, toughened and laminated to Ug, warm edge, DLF, edge trim and offcut, each linked to the page of this site that deals with it.Example 57 terms, every figure from its page

Cutting and the workshop

From the measurement of the hole to the label on the pane: nesting, the cutting plan and the offcuts already on the rack.

How to measure an opening for glassMeasure the hole, not the pane in it: three widths, three heights, the smallest of each, and both diagonals. Then the deduction, which pulls against the edge cover the frame still has to keep. It matters because toughened glass cannot be trimmed — 4 mm oversize is a new pane and another week.Example the measurement nobody takes: the diagonals
Glass cut to size: how to measure, choose and order itWhat the glass shop needs: the finished size, the thickness for what the glass carries, toughened or laminated, the edges and the holes.Example a 1200 × 700 top on a frame: 8 mm toughened
How much glass do you throw away?Sheets a month, your yield and the price per m²: the glass binned in a year in m² and euros, and what a yield of your choosing would change. The sum with your figures, no promises.Example 20 DLF sheets a month at 70 %: €14,561 a year
Cutting planThe shop-floor half of the optimiser. Every piece labelled on the diagram, the cuts listed in the order the table makes them with the measurement for each one, and each offcut with its real size so it goes back on the rack under a number instead of into the bin.Example prints on A4, one page per sheet — no account, nothing uploaded
Cutting labelsThe job every shop does with a marker pen while the panes are still on the table. One label per pane, straight out of the solved nest and in the order the table cuts them: the same piece code as the plan, the size, the glass, which sheet it came off, and whether it was rotated.Example plain A4 or 70 × 37 mm label sheets — 24 to a page, exact
Offcut inventoryThe rack against your wall is glass you have already paid for. List it, and the optimiser cuts the next order out of it before it buys a sheet — but only opens a piece when doing so removes a whole sheet from the order, so good stock is not fragmented for nothing.Example on one 40-piece job: 4 sheets down to 2, 398 € not spent
Glass cutting software comparedoptiCutter, Optimik, CutOptim, MaxCut, Smart Glazier and the industrial suites side by side: the price each one publishes, whether it is made for glass, whether it cuts from your offcuts first and where it runs, with the source of every figure.Example nine programs, every price with its source
Glass sheet sizesJumbo (PLF) 6000 × 3210, DLF 3210 × 2250, half and quarter sheets: what each weighs at every thickness, how many doors, shower screens and windows one sheet gives, and the optimiser loaded with that sheet.Example a DLF sheet of 6 mm: 108.3 kg
Three cutting jobs worked outA shower screen, the windows of a small building job and a shop, each run through the cutting optimiser: sheets to buy, yield, offcuts back on the rack and scrap, a drawing of every sheet and the order one click away.Example the shower screen: 1 sheet, 77.5 % yield, 1.8 % scrap
How to cut glassGlass is scored and snapped, so every cut runs edge to edge: the edge trim, strips, columns and panes, the order of the list and the offcuts, drawn on a real sheet with every cut numbered.Example one order, six orderings: 2 to 3 sheets

On site: what is this glass?

Field guides for the questions a pane asks you: why it broke, where the mist is, toughened or not, low iron or not.

Why did this glass break?Cracks branch away from the origin and never towards it, so following them backwards finds where it started — and what sits there is the answer. Impact, thermal stress, edge damage or a nickel sulphide inclusion, each with its own signature, and the argument about who pays usually turns on which one it is.Example toughened with no strike mark is not automatically nickel sulphide
Misted double glazingThe water sits on one of four surfaces and only one of them means the window has failed. Wipe it inside, wipe it outside: if neither reaches it, it is in the sealed cavity, the seal has gone and the desiccant is saturated. That unit is replaced whole.Example condensation on the outside means it is insulating well
Where safety glass is requiredThe hazardous locations of IRC R308.4 and the critical locations of Approved Document K, checked for your pane.Example window, bottom edge at 300 mm, 1.2 m² → Required · US and England
Is this glass toughened or annealed?Five checks in the order worth doing them: the permanent mark to EN 12150-1, the polarised-light test you can run with sunglasses on installed glass, what the edges and the roller wave tell you, what the pane's own history rules out, and the break pattern that is certain and destroys the evidence. Plus why a toughened pane sometimes breaks with nobody near it.Example Spots that move when you tilt your head — toughened
Low iron, or ordinary clear float?Sight along the edge and ordinary float is green, low iron is not — but your eye adapts within seconds, so a single pane on its own is a guess. What to compare it against, the white paper test, why the green builds with thickness, and the jobs where it costs you an argument: white splashbacks, balustrade edges, glass floors and shopfronts.Example Doubled light path — a white splashback comes out pale green