Thickness is the specification buyers revise most often between the first quote and the second, and it is the one that moves price fastest. It is also the one where the intuitive fix — add a millimetre — is frequently the expensive way to solve a problem that a support rib or a shorter shelf would have solved for the cost of a bracket.
This guide covers how acrylic behaves under real retail loads, which gauges a Chinese fabricator stocks and quotes without a surcharge, and how to write thickness into a request for quotation so three factories price the same part. Whether the part should be acrylic at all is a separate decision, covered in our comparison of acrylic, PETG and polycarbonate for retail displays.
What thickness actually controls
Four things move when you change a gauge, and they do not move together.
- Bending stiffness. The stiffness of a flat panel rises with roughly the cube of its thickness. Going from 3 mm to 6 mm makes a shelf around eight times stiffer, not twice.
- Edge appearance. On a display the polished edge is a visible design element. Below about 3 mm the edge reads as a line; from 5 mm upward it reads as a bar of light, and a diamond-polished edge at 10 mm or more starts to look like glass.
- Joint options. Slot-and-tab joints, screw bosses and threaded inserts need material to bite into. Under about 5 mm most fabricators will move you to solvent bonding or external brackets.
- Weight. Cast acrylic has a density of about 1.19 g/cm³. One square metre weighs roughly 3.6 kg at 3 mm, about 6 kg at 5 mm and about 11.9 kg at 10 mm.
Because these four move at different rates, “make it thicker” is rarely the whole answer, and on a large order it is seldom the cheap one.
The gauges a Chinese fabricator will actually quote
Cast acrylic sheet is commonly stocked in 2, 3, 4, 5, 6, 8, 10, 12, 15, 20, 25 and 30 mm. Anything on that list is a stock purchase. Anything off it is a special mill order, which adds both lead time and a minimum sheet quantity that a display programme rarely absorbs comfortably. Before you specify 7 mm, check whether 6 or 8 does the job.
Two conventions are worth knowing before the first quote comes back.
Nominal thickness is a label, not a measurement. Cast sheet carries a wider thickness tolerance than extruded sheet because of how it is made, so a 5 mm cast panel and a 5 mm milled slot will not necessarily fit each other. A competent fabricator solves this by cutting the slot to the measured sheet, which works provided your drawing asks for a fit rather than a dimension. Ask which tolerance the factory works to and put the answer in the file.
Imperial-origin specs still circulate. One eighth of an inch is 3.175 mm and one quarter inch is 6.35 mm. A factory quoting from a metric stock list will substitute 3 mm and 6 mm unless the drawing says otherwise, which is usually the right call — but it should be a decision, not a surprise. This belongs in the drawing, alongside the other items in our product spec sheet guide.
Span, not thickness, is usually what fails
A shelf that bows is usually a span problem wearing a thickness costume.
For a uniformly loaded panel supported at two edges, deflection rises with roughly the fourth power of the unsupported span and falls with roughly the cube of the thickness. The practical consequence is worth reading twice: halving the span cuts deflection by around sixteen times, while doubling the thickness cuts it by around eight. Doubling thickness also doubles the material cost of that part and adds weight to every carton. A centre support costs a bracket.
Three ways to shorten the span without touching the gauge:
- Add a centre support or a vertical divider. On a shop-fitting shelf this is often already justified by the merchandising layout.
- Turn the front edge down into a return flange. A folded or bonded lip a few centimetres deep stiffens a shelf far more than the same material spread across its thickness, because it moves material away from the neutral axis.
- Reduce the depth, or move to a bracketed design. Deep unsupported shelves are the most common source of the complaint.
Raise these before you argue about millimetres. A fabricator running a first sample round can usually test a stiffening rib against a thicker sheet in the same week, and the rib is normally the cheaper unit.
The load that does not go away: creep
Acrylic is a thermoplastic. Under sustained load it deforms slowly and does not fully recover, a behaviour called creep. A shelf loaded to a deflection you accepted on day one can read visibly bowed after several months of continuous stock, and heat accelerates it — a unit in a sunlit window, or under a close-mounted lamp, creeps faster than the same unit in a cool aisle.
Three things follow from that:
- Specify for the load the shelf carries every day, not the load in the sample photograph.
- For a display that stays loaded, design for a deflection you would consider over-stiff when new.
- Ask whether the sample was loaded for its evaluation period. A sample that sat empty on a desk for a fortnight has told you nothing about creep.
A related failure is crazing: fine hairline cracks around screw holes and bonded joints, caused by residual stress from machining and solvent bonding and usually triggered later by cleaning chemicals or sustained load. Annealing the parts after fabrication relieves that stress. Ask whether annealing is included in the process, and specify it if it is not.
Thickness by display type
The table below reflects the gauges a fabricator will suggest before seeing a drawing. Treat them as a starting point for the conversation rather than engineering values — the correct figure depends on span, load, support condition and how much deflection your brand will accept.
| Display element | Typical gauge | What drives the choice |
|---|---|---|
| Countertop riser or tiered stand | 3–5 mm | Light product over short spans; edge appearance matters more than load |
| Literature or brochure holder | 2–3 mm | Formed from a single sheet; thinner material bends more cleanly |
| Loaded shelf, span around 300 mm | 5–8 mm | Deflection and creep rather than outright strength |
| Loaded shelf, span 600 mm or more | 8–12 mm, or a thinner sheet plus a centre support | Span dominates; the support is usually the cheaper answer |
| Vertical panel or sign face | 3–5 mm | Rigidity for handling and installation; rarely load-bearing |
| Enclosure or lockable case body | 5–8 mm | Hardware bite, rigidity of the box, and how the door feels in the hand |
| Column, plinth or pedestal | 8–15 mm | Perceived solidity, edge presence, resistance to knocks in a busy aisle |
| Base plate under a tall unit | 10–20 mm | Stability and tipping resistance rather than bending |
Category context changes the emphasis. A 3C electronics display is often specified around security fittings and cable routing, a vape point-of-purchase unit around lockable access and counter footprint, and a cosmetics counter unit around edge quality at eye level.
What thickness costs you in freight
Whether thickness shows up on the freight invoice depends on how the display ships.
Assembled units are usually charged on dimensional weight. The carton is mostly air and protective packaging, so the packed envelope sets the price and the gauge barely registers. Flat-packed panels are usually charged on actual weight, and there thickness is the bill: at one square metre per unit, moving from 5 mm to 10 mm roughly doubles the shipping weight of the part.
The consequence is that a gauge decision and a packing decision should be made together rather than in sequence. If a unit is going to travel assembled by air, spending money on thinner sheet buys you very little; if it flat-packs into a carton by sea or into a fulfilment network, every millimetre is recurring cost. Duty and landed-cost treatment are covered separately in our guide to importing acrylic displays into the United States.
Putting thickness in the RFQ so the quotes come back comparable
Most non-comparable quotes for acrylic displays differ because the factories filled the same gaps differently. Six lines close the gaps:
- Nominal thickness per part, not per assembly. A single figure for a multi-part unit invites each factory to guess differently.
- Cast or extruded, and whether you will accept either.
- The deflection you will accept at a stated load and span, as a measured figure in millimetres.
- Edge finish per edge — flame-polished, diamond-polished or as-cut — specified only where the edge is visible, since finishing hidden edges is money spent on nothing.
- Joint method, or an explicit invitation for the fabricator to propose one.
- Whether parts are annealed after machining and bonding.
Our acrylic display RFQ template sets these out in a form you can send, and the wider process from shortlist to first container is covered in the seven-step sourcing playbook. If your unit needs a mould rather than sheet fabrication, tooling costs change the arithmetic again. A quote that arrives without asking a single question about any of the six is a quote priced on assumptions.
Yixinheng Acrylic is a verified factory on ChinaMakersHub, working out of Pingshan, Shenzhen with 26 years of acrylic manufacturing experience, complete in-house equipment and seven-day sampling on build-to-order work. It accepts both OEM briefs supplied as drawings and ODM work developed from a concept, across cosmetic, vape and 3C electronics display lines that run the full gauge range described here. Buyers comparing Shenzhen suppliers may also want the wider Shenzhen sourcing guide and the custom POS display overview.
Common questions
What thickness of acrylic should I use for a retail display shelf?
A retail display shelf carrying light product over a span of about 300 millimetres is commonly specified in 5 to 8 millimetre cast acrylic, while spans approaching 600 millimetres move to 8 to 12 millimetres or keep a thinner sheet and add a centre support. The right figure depends on the load, the unsupported span and how much deflection the brand will accept, so treat any table value as the opening position for a design-for-manufacture review rather than as an answer.
Does thicker acrylic fix a sagging shelf?
Thicker acrylic does reduce sagging, because bending stiffness rises with roughly the cube of thickness, but shortening the unsupported span is usually the cheaper fix, since deflection rises with roughly the fourth power of span. Halving a span therefore does more than doubling a gauge, and a centre support or a turned-down front lip costs a fraction of the extra material across a production run.
What is the difference between 3 mm and 1/8 inch acrylic?
One eighth of an inch is 3.175 millimetres, so it is marginally thicker than a 3 millimetre metric sheet, and Chinese fabricators quoting from a metric stock list will normally substitute the 3 millimetre gauge unless the drawing states otherwise. The difference is immaterial for strength but it matters for slot-and-tab joints, channel fits and anything that has to mate with existing imperial parts.
Why did my acrylic display crack around the screw holes?
Hairline cracking around screw holes and bonded joints in acrylic is usually crazing caused by residual stress left by machining or solvent bonding, and it is often triggered later by cleaning chemicals or by load that stays on the part. Annealing after fabrication relieves that stress, so ask whether it is part of the process and write it into the drawing if it is not.
Does acrylic thickness affect shipping cost?
Acrylic thickness affects shipping cost mainly on flat-packed panel shipments, which are charged on actual weight, since one square metre of acrylic weighs about 3.6 kilograms at 3 millimetres and about 11.9 kilograms at 10 millimetres. Assembled displays are more often charged on dimensional weight, where the packed carton size rather than the sheet gauge sets the price, so the packing format should be decided alongside the gauge.
Thickness is worth getting right because it is one of the few display specifications that is simultaneously a structural decision, an appearance decision and a recurring freight cost. Settle the span first, then the gauge, then the packing — in that order the numbers tend to argue with each other far less.