Acrylic Sheet Thickness Guide for Common Projects

Choosing the right acrylic thickness is important. A sheet that is too thin may flex, bow or crack, while an unnecessarily thick sheet can add weight and cost to your project.

The best thickness depends on how the acrylic will be used, the size of the panel, how it will be supported and whether it may experience weight, wind or impact. This Plastic Warehouse practical guide covers common applications, including tabletops, signs, shelves, windows, splashbacks and picture frames.

Plastic Warehouse Quick Acrylic Thickness Guide

Acrylic Thickness for Tabletops

Protecting an existing tabletop

A 3 mm acrylic sheet is suitable for many desks, bedside tables and smaller surfaces. It provides a clear protective layer against spills, marks and everyday wear.

For larger dining tables or areas that receive heavier use, 4.5 mm or 5 mm acrylic provides additional rigidity and feels more substantial.

Because the acrylic is fully supported by the surface underneath, it usually does not need to be especially thick.

Freestanding acrylic tabletops

If the acrylic will span between legs or supports, thickness becomes much more important. A starting point of 8–12 mm may suit smaller, properly supported tabletops. Larger tables or longer unsupported spans may require considerably thicker material.

The required thickness depends on:

• The length and width of the tabletop
• The distance between supports
• The expected weight placed on it
• The position and design of the legs
• Whether people may lean or sit on the edge

Acrylic should not be selected for a load-bearing tabletop using thickness alone. The complete support structure needs to be considered.

Acrylic Thickness for Signs

For small indoor signs, nameplates and decorative lettering, 3 mm acrylic is generally a practical choice. It is lightweight, easy to handle and suitable for laser cutting, engraving and printing.

For larger wall-mounted signs, 4.5 mm or 5 mm acrylic provides greater stiffness and a more substantial appearance.

Freestanding signs, projecting panels and larger outdoor signs may require 6 mm acrylic or thicker, depending on their dimensions and fixing method.

When selecting acrylic for an outdoor sign, also consider:

• Wind exposure
• The number and position of fixings
• Distance between supports
• Thermal expansion
• Whether the sign is mounted flat or projects from a wall

Avoid overtightening screws against the acrylic. Holes should provide suitable clearance, and compatible washers or stand-off fixings can help distribute pressure.

Acrylic Thickness for Shelves

Acrylic shelves need enough thickness to resist bending under load. The longer and deeper the shelf, the more likely it is to flex.

A 6 mm sheet may be suitable for a small shelf that is supported along the back and sides and only holds lightweight objects.

For wider shelves or heavier items, consider 8–12 mm acrylic and additional brackets or supports. Long shelves may still bend even when made from relatively thick acrylic, particularly when supported only at each end.

Shelf thickness should be based on:

• The unsupported span
• Shelf depth
• Expected load
• Number and location of brackets
• Whether the load is evenly distributed

Adding a central bracket can often reduce flex more effectively than simply increasing the sheet thickness.

Acrylic Thickness for Windows and Replacement Glazing

Acrylic is commonly used to replace glass in sheds, cabinet doors, playhouses, display cases, internal partitions and other non-structural glazing applications.

For small cabinet doors and display windows, 3–4.5 mm acrylic is often suitable.

For larger panels, 4.5–6 mm acrylic offers improved rigidity. Large exterior windows or panels exposed to wind may require 8–10 mm or thicker, together with an appropriate frame and installation system.

The sheet must have enough room to expand and contract as temperatures change. Acrylic has a greater rate of thermal expansion than glass, so it should not be tightly trapped inside a frame. Manufacturer data identifies thermal movement as an important design consideration for acrylic installations. PLEXIGLAS® technical information

For security glazing, machine guards or areas exposed to substantial impact, polycarbonate may be more appropriate than standard acrylic.

Acrylic Thickness for Splashbacks

Acrylic splashbacks provide a smooth, modern surface for kitchens, laundries and bathrooms.

A thickness of 3–5 mm is generally suitable when the sheet is installed flat against a solid wall. Because the wall supports the entire panel, additional thickness is usually unnecessary.

Before using acrylic as a splashback, check:

• The distance from cooktops and other heat sources
• The adhesive’s compatibility with acrylic
• The condition and flatness of the wall
• Allowance for expansion
• Relevant building and fire requirements

Standard acrylic should not be installed directly behind a gas cooktop or close to an open flame. Where heat or fire compliance is a concern, confirm the applicable Australian requirements before choosing the material.

Acrylic Thickness for Picture Frames

For small photographs and certificates, 2–3 mm acrylic is lightweight and easy to fit into standard frames.

For posters, artwork and larger photographs, 3 mm acrylic is a reliable general-purpose choice. Larger frames may benefit from 4.5 mm acrylic, particularly when additional stiffness is required.

The correct thickness also depends on the frame rebate—the recessed area that holds the glazing, artwork and backing board. Make sure the complete assembly will fit before ordering thicker material.

Special acrylic grades are also available for valuable or frequently viewed artwork, including:

• UV-resistant acrylic
• Anti-reflective acrylic
• Abrasion-resistant acrylic
• Gallery and conservation glazing products

Check out our Plexiglass for framing here

Why Panel Size Matters

Two sheets made from the same material and thickness can perform very differently if their dimensions are different.

A 500 × 300 mm sheet may feel rigid, while a 1800 × 900 mm sheet of the same thickness may flex noticeably. As the unsupported area increases, the panel generally needs to be thicker or supported at more points.

You should also consider whether the sheet will be:

• Fully supported against another surface
• Fixed around all four edges
• Held only at two ends
• Installed vertically or horizontally
• Used indoors or exposed to outdoor weather
• Subjected to weight, impact or vibration

Is Thicker Acrylic Always Better?

Not necessarily. Thicker acrylic provides more stiffness and a substantial appearance, but it is also heavier and generally more expensive.

For a fully supported splashback or tabletop cover, increasing the thickness may provide little practical benefit. However, a shelf or freestanding tabletop must resist bending, making thickness and support far more important.

The goal is to select a thickness that provides suitable performance without paying for more material than the project needs.

PLEXIGLAS® Soundstop for Noise Barriers

For projects where reducing noise is the main priority, standard acrylic may not be the most suitable option. PLEXIGLAS® Soundstop is a specialised transparent acrylic designed for noise-control applications, including:

• Roadside noise barriers
• Railway infrastructure
• Bridges and wind barriers
• Transport facilities
• Commercial and community developments

PLEXIGLAS® Soundstop combines high transparency with effective airborne sound reduction. This allows noise barriers to reduce sound without creating a dark, enclosed or tunnel-like environment.

It is commonly available in 15 mm, 20 mm and 25 mm thicknesses. As the sheet becomes thicker, its sound-reduction performance generally improves. Manufacturer data lists weighted sound reduction values of approximately, 30 dB at 15 mm, 32 dB at 20 mm and 33 dB at 25 mm, depending on the product grade and testing standard. PLEXIGLAS® Soundstop technical information

The correct thickness must be determined by the required acoustic performance, panel dimensions, support spacing, wind load and engineering requirements. Large outdoor noise-barrier installations should always be designed and approved by suitably qualified professionals.

Need to order Acrylic Cut to size? check out our options below.

Coloured Acrylic cut to size

Clear Acrylic cut to size

Mirrored Acrylic cut to size

LED Acrylic for illuminated displays

Impact resistant Acrylic